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24 files changed, 6240 insertions, 0 deletions

diff --git a/Engineering_Physics_by_G._Aruldhas/Chapter10_1.ipynb b/Engineering_Physics_by_G._Aruldhas/Chapter10_1.ipynb
new file mode 100755
index 00000000..a64ad6b4
--- /dev/null
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@@ -0,0 +1,300 @@
+{
+ "metadata": {
+  "name": "",
+  "signature": "sha256:78b8d610d2cc37c12bbe36fc70ba217f440b3e2b1b7e7cbb3aa498d471c77bb0"
+ },
+ "nbformat": 3,
+ "nbformat_minor": 0,
+ "worksheets": [
+  {
+   "cells": [
+    {
+     "cell_type": "heading",
+     "level": 1,
+     "metadata": {},
+     "source": [
+      "10: Statistical Mechanics"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 10.1, Page number 222"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "from __future__ import division\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "k = 1.38*10**-23;    #Boltzmann constant(J/K)\n",
+      "e = 1.6*10**-19;     #Energy equivalent of 1 eV(J/eV)\n",
+      "g1 = 2;    #The degeneracy of ground state\n",
+      "g2 = 8;    #The degeneracy of excited state\n",
+      "delta_E = 10.2;     #Energy of excited state above the ground state(eV)\n",
+      "T = 6000;    #Temperature of the state(K)\n",
+      "\n",
+      "#Calculation\n",
+      "D_ratio = g2/g1;    #Ratio of degeneracy of states\n",
+      "x = k*T/e;\n",
+      "N_ratio = D_ratio*math.exp(-delta_E/x);     #Ratio of occupancy of the excited to the ground state\n",
+      "\n",
+      "#Result\n",
+      "print \"The ratio of occupancy of the excited to the ground state is\",N_ratio"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The ratio of occupancy of the excited to the ground state is 1.10167326887e-08\n"
+       ]
+      }
+     ],
+     "prompt_number": 1
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 10.2, Page number 222"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "a = 10/2;\n",
+      "#enegy of 10 bosons is E = (10*pi**2*h**2)/(2*m*a**2) = (5*pi**2*h**2)/(m*a**2)\n",
+      "\n",
+      "#Result\n",
+      "print \"enegy of 10 bosons is E = \",int(a),\"(pi**2*h**2)/(m*a**2)\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "enegy of 10 bosons is E =  5 (pi**2*h**2)/(m*a**2)\n"
+       ]
+      }
+     ],
+     "prompt_number": 5
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 10.3, Page number 223"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "n1=1;    #1st level\n",
+      "n2=2;    #2nd level\n",
+      "n3=3;    #3rd level\n",
+      "n4=4;    #4th level\n",
+      "n5=5;    #5th level\n",
+      "\n",
+      "#Calculation\n",
+      "#an energy level can accomodate only 2 fermions. hence there will be 2 fermions in each level\n",
+      "#thus total ground state energy will be E = (2*E1)+(2*E2)+(2*E3)+(2*E4)+E5\n",
+      "#let X = ((pi**2)*(h**2)/(2*m*a**2)). E = X*((2*n1**2)+(2*n2**2)+(2*n3**2)+(2*n4**2)+(n5**2))\n",
+      "A = (2*n1**2)+(2*n2**2)+(2*n3**2)+(2*n4**2)+(n5**2);\n",
+      "#thus E = A*X\n",
+      "\n",
+      "#Result\n",
+      "print \"the ground state energy of the system is\",A,\"(pi**2)*(h**2)/(2*m*a**2)\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "the ground state energy of the system is 85 (pi**2)*(h**2)/(2*m*a**2)\n"
+       ]
+      }
+     ],
+     "prompt_number": 6
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 10.4, Page number 223"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "e = 1.6*10**-19;    #Energy equivalent of 1 eV(J/eV)\n",
+      "N_A = 6.02*10**23;    #Avogadro's number\n",
+      "h = 6.626*10**-34;    #Planck's constant(Js)\n",
+      "me = 9.1*10**-31;    #Mass of electron(kg)\n",
+      "rho = 10.5;    #Density of silver(g/cm)\n",
+      "m = 108;    #Molecular mass of silver(g/mol)\n",
+      "\n",
+      "#Calculation\n",
+      "N_D = rho*N_A/m;    #Number density of conduction electrons(per cm**3)\n",
+      "N_D = N_D*10**6;    #Number density of conduction electrons(per m**3)\n",
+      "E_F = ((h**2)/(8*me))*(3/math.pi*N_D)**(2/3);     #fermi energy(J)\n",
+      "E_F = E_F/e;          #fermi energy(eV)\n",
+      "E_F = math.ceil(E_F*10**2)/10**2;     #rounding off the value of E_F to 2 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The number density of conduction electrons is\",N_D, \"per metre cube\"\n",
+      "print \"The Fermi energy of silver is\",E_F, \"eV\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The number density of conduction electrons is 5.85277777778e+28 per metre cube\n",
+        "The Fermi energy of silver is 5.51 eV\n"
+       ]
+      }
+     ],
+     "prompt_number": 7
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 10.5, Page number 224"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "N_A = 6.02*10**23;     #Avogadro's number\n",
+      "k = 1.38*10**-23;      #Boltzmann constant(J/K)\n",
+      "T = 293;     #Temperature of sodium(K)\n",
+      "E_F = 3.24;    #Fermi energy of sodium(eV)\n",
+      "e = 1.6*10**-19;    #Energy equivalent of 1 eV(J/eV)\n",
+      "\n",
+      "#Calculation\n",
+      "C_v = math.pi**2*N_A*k**2*T/(2*E_F*e);     #Molar specific heat of sodium(per mole)\n",
+      "C_v = math.ceil(C_v*10**2)/10**2;     #rounding off the value of C_v to 2 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The electronic contribution to molar specific heat of sodium is\",C_v, \"per mole\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The electronic contribution to molar specific heat of sodium is 0.32 per mole\n"
+       ]
+      }
+     ],
+     "prompt_number": 8
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 10.6, Page number 224"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "e = 1.6*10**-19;    #Energy equivalent of 1 eV(J/eV)\n",
+      "h = 6.626*10**-34;     #Planck's constant(Js)\n",
+      "m = 9.1*10**-31;       #Mass of the electron(kg)\n",
+      "N_D = 18.1*10**28;       #Number density of conduction electrons in Al(per metre cube)\n",
+      "\n",
+      "#Calculation\n",
+      "E_F = h**2/(8*m)*(3/math.pi*N_D)**(2/3);     #N_D = N/V. Fermi energy of aluminium(J)\n",
+      "E_F = E_F/e;      #Fermi energy of aluminium(eV)\n",
+      "E_F = math.ceil(E_F*10**3)/10**3;     #rounding off the value of E_F to 3 decimals\n",
+      "Em_0 = 3/5*E_F;     #Mean energy of  the electron at 0K(eV)\n",
+      "Em_0 = math.ceil(Em_0*10**3)/10**3;     #rounding off the value of Em_0 to 3 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The Fermi energy of aluminium is\",E_F, \"eV\"\n",
+      "print \"The mean energy of  the electron is\",Em_0, \"eV\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The Fermi energy of aluminium is 11.696 eV\n",
+        "The mean energy of  the electron is 7.018 eV\n"
+       ]
+      }
+     ],
+     "prompt_number": 9
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": []
+    }
+   ],
+   "metadata": {}
+  }
+ ]
+}
\ No newline at end of file
diff --git a/Engineering_Physics_by_G._Aruldhas/Chapter11_1.ipynb b/Engineering_Physics_by_G._Aruldhas/Chapter11_1.ipynb
new file mode 100755
index 00000000..d5495309
--- /dev/null
+++ b/Engineering_Physics_by_G._Aruldhas/Chapter11_1.ipynb
@@ -0,0 +1,326 @@
+{
+ "metadata": {
+  "name": "",
+  "signature": "sha256:ecf05dc207884a73f4d33d07fdee310eee827214d9664476e0cf941cf4d4f512"
+ },
+ "nbformat": 3,
+ "nbformat_minor": 0,
+ "worksheets": [
+  {
+   "cells": [
+    {
+     "cell_type": "heading",
+     "level": 1,
+     "metadata": {},
+     "source": [
+      "11: Lasers"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 11.1, Page number 249"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "h = 6.626*10**-34;     #Planck's constant(Js)\n",
+      "c = 3*10**8;     #Speed of light in free space(m/s)\n",
+      "k = 1.38*10**-23;     #Boltzmann constant(J/K)\n",
+      "T = 300;     #Temperature at absolute scale(K)\n",
+      "lamda1 = 5500;     #Wavelength of visible light(A)\n",
+      "lamda2 = 10**-2;     #Wavelength of microwave(m)\n",
+      "\n",
+      "#Calculation\n",
+      "lamda1 = lamda1*10**-10;     #Wavelength of visible light(m)\n",
+      "rate_ratio = math.exp(h*c/(lamda1*k*T))-1;    #Ratio of spontaneous emission to stimulated emission\n",
+      "rate_ratio1 = math.exp(h*c/(lamda2*k*T))-1;     #Ratio of spontaneous emission to stimulated emission\n",
+      "rate_ratio1 = math.ceil(rate_ratio1*10**5)/10**5;     #rounding off the value of rate_ratio1 to 5 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The ratio of spontaneous emission to stimulated emission for visible region is\",rate_ratio\n",
+      "print \"The ratio of spontaneous emission to stimulated emission for microwave region is\", rate_ratio1"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The ratio of spontaneous emission to stimulated emission for visible region is 8.19422217477e+37\n",
+        "The ratio of spontaneous emission to stimulated emission for microwave region is 0.00482\n"
+       ]
+      }
+     ],
+     "prompt_number": 3
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 11.2, Page number 250"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "e = 1.6*10**-19;   #Energy equivalent of 1 eV(J/eV)\n",
+      "h = 6.626*10**-34;    #Planck's constant(Js)\n",
+      "c = 3*10**8;    #Speed of light in free space(m/s)\n",
+      "lamda = 690;    #Wavelength of laser light(nm)\n",
+      "E_lower = 30.5;    #Energy of lower state(eV)\n",
+      "\n",
+      "#Calculation\n",
+      "lamda = lamda*10**-9;     #Wavelength of laser light(m)\n",
+      "E = h*c/lamda;    #Energy of the laser light(J)\n",
+      "E = E/e;     #Energy of the laser light(eV)\n",
+      "E_ex = E_lower + E;    #Energy of excited state of laser system(eV)\n",
+      "E_ex = math.ceil(E_ex*10**2)/10**2;     #rounding off the value of E_ex to 2 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The energy of excited state of laser system is\",E_ex, \"eV\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The energy of excited state of laser system is 32.31 eV\n"
+       ]
+      }
+     ],
+     "prompt_number": 4
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 11.3, Page number 250"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "import numpy as np\n",
+      "\n",
+      "#Variable declaration\n",
+      "h = 6.626*10**-34;     #Planck's constant(Js)\n",
+      "k = 1.38*10**-23;      #Boltzmann constant(J/K)\n",
+      "\n",
+      "#Calculation\n",
+      "#Stimulated Emission = Spontaneous Emission <=> exp(h*f/(k*T))-1 = 1 i.e.\n",
+      "#f/T = log(2)*k/h = A\n",
+      "A =  np.log(2)*k/h;     #Frequency per unit temperature(Hz/K)\n",
+      "A = A/10**10;\n",
+      "A = math.ceil(A*10**3)/10**3;     #rounding off the value of A to 3 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The stimulated emission equals spontaneous emission iff f/T =\",A,\"*10**10 Hz/k\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The stimulated emission equals spontaneous emission iff f/T = 1.444 *10**10 Hz/k\n"
+       ]
+      }
+     ],
+     "prompt_number": 7
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 11.4, Page number 250"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "lamda = 500;     #Wavelength of laser light(nm)\n",
+      "f = 15;     #Focal length of the lens(cm)\n",
+      "d = 2;      #Diameter of the aperture of source(cm)\n",
+      "P = 5;      #Power of the laser(mW)\n",
+      "\n",
+      "#Calculation\n",
+      "P =  P*10**-3;    #Power of the laser(W)\n",
+      "lamda = lamda*10**-9;      #Wavelength of laser light(m)\n",
+      "d = d*10**-2;      #Diameter of the aperture of source(m)\n",
+      "f = f*10**-2;      #Focal length of the lens(m)\n",
+      "a = d/2;    #Radius of the aperture of source(m)\n",
+      "A = math.pi*lamda**2*f**2/a**2;     #Area of the spot at the focal plane, metre square\n",
+      "I = P/A;     #Intensity at the focus(W/m**2)\n",
+      "I = I/10**7;\n",
+      "I = math.ceil(I*10**4)/10**4;     #rounding off the value of I to 1 decimal\n",
+      "\n",
+      "#Result\n",
+      "print \"The area of the spot at the focal plane is\",A, \"m**2\"\n",
+      "print \"The intensity at the focus is\",I,\"*10**7 W/m**2\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The area of the spot at the focal plane is 1.76714586764e-10 m**2\n",
+        "The intensity at the focus is 2.8295 *10**7 W/m**2\n"
+       ]
+      }
+     ],
+     "prompt_number": 14
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 11.5, Page number 251"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "h = 6.626*10**-34;     #Planck's constant(Js)\n",
+      "c = 3*10**8;     #Speed of light in free space(m/s)\n",
+      "lamda = 1064;    #Wavelength of laser light(nm)\n",
+      "P = 0.8;    #Average power output per laser pulse(W)\n",
+      "dt = 25;    #Pulse width of laser(ms)\n",
+      "\n",
+      "#Calculation\n",
+      "dt = dt*10**-3;       #Pulse width of laser(s)\n",
+      "lamda = lamda*10**-9;     #Wavelength of laser light(m)\n",
+      "E = P*dt;   #Energy released per pulse(J)\n",
+      "E1 = E*10**3;\n",
+      "N = E/(h*c/lamda);    #Number of photons in a pulse\n",
+      "\n",
+      "#Result\n",
+      "print \"The energy released per pulse is\",E1,\"*10**-3 J\"\n",
+      "print \"The number of photons in a pulse is\", N\n"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The energy released per pulse is 20.0 *10**-3 J\n",
+        "The number of photons in a pulse is 1.07053023443e+17\n"
+       ]
+      }
+     ],
+     "prompt_number": 17
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 11.6, Page number 251"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "lamda = 693;     #Wavelength of laser beam(nm)\n",
+      "D = 3;       #Diameter of laser beam(mm)\n",
+      "d = 300;    #Height of a satellite above the surface of earth(km)\n",
+      "\n",
+      "#Calculation\n",
+      "D = D*10**-3;    #Diameter of laser beam(m)\n",
+      "lamda = lamda*10**-9;     #Wavelength of laser beam(m)\n",
+      "d = d*10**3;     #Height of a satellite above the surface of earth(m)\n",
+      "d_theta = 1.22*lamda/D;    #Angular spread of laser beam(rad)\n",
+      "dtheta = d_theta*10**4;\n",
+      "dtheta = math.ceil(dtheta*10**2)/10**2;     #rounding off the value of dtheta to 2 decimals\n",
+      "a = d_theta*d;      #Diameter of the beam on the satellite(m)\n",
+      "a = math.ceil(a*10)/10;     #rounding off the value of a to 1 decimal\n",
+      "\n",
+      "#Result\n",
+      "print \"The height of a satellite above the surface of earth is\",dtheta,\"*10**-4 rad\"\n",
+      "print \"The diameter of the beam on the satellite is\",a, \"m\"\n"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The height of a satellite above the surface of earth is 2.82 *10**-4 rad\n",
+        "The diameter of the beam on the satellite is 84.6 m\n"
+       ]
+      }
+     ],
+     "prompt_number": 25
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": []
+    }
+   ],
+   "metadata": {}
+  }
+ ]
+}
\ No newline at end of file
diff --git a/Engineering_Physics_by_G._Aruldhas/Chapter12_1.ipynb b/Engineering_Physics_by_G._Aruldhas/Chapter12_1.ipynb
new file mode 100755
index 00000000..7fa73024
--- /dev/null
+++ b/Engineering_Physics_by_G._Aruldhas/Chapter12_1.ipynb
@@ -0,0 +1,237 @@
+{
+ "metadata": {
+  "name": "",
+  "signature": "sha256:aab26783619c45961eca2004893b5ed3a4fe23aa4a44df9efa3d63c5d1ff3388"
+ },
+ "nbformat": 3,
+ "nbformat_minor": 0,
+ "worksheets": [
+  {
+   "cells": [
+    {
+     "cell_type": "heading",
+     "level": 1,
+     "metadata": {},
+     "source": [
+      "12: Holography and Fibre Optics"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 12.1, Page number 271"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "n1 = 1.43;    #Refractive index of fibre core\n",
+      "n2 = 1.4;     #Refractive index of fibre cladding\n",
+      "\n",
+      "#Calculation\n",
+      "#As sin (alpha_c) = n2/n1, solving for alpha_c\n",
+      "alpha_c = math.asin(n2/n1);     #Critical angle for optical fibre(rad)\n",
+      "alpha_c = alpha_c*57.2957795;     #Critical angle for optical fibre(degrees)\n",
+      "alpha_c = math.ceil(alpha_c*10**3)/10**3;     #rounding off the value of alpha_c to 3 decimals\n",
+      "#AS cos(theta_c) = n2/n1, solving for theta_c\n",
+      "theta_c = math.acos(n2/n1);    #Critical propagation angle for optical fibre(rad)\n",
+      "theta_c = theta_c*57.2957795;     #Critical propagation angle for optical fibre(degrees)\n",
+      "theta_c = math.ceil(theta_c*10**2)/10**2;     #rounding off the value of theta_c to 2 decimals\n",
+      "NA = math.sqrt(n1**2 - n2**2);     #Numerical aperture for optical fibre\n",
+      "NA = math.ceil(NA*10**3)/10**3;     #rounding off the value of NA to 3 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The critical angle for optical fibre is\",alpha_c, \"degrees\"\n",
+      "print \"The critical propagation angle for optical fibre is\",theta_c, \"degrees\"\n",
+      "print \"Numerical aperture for optical fibre is\",NA\n"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The critical angle for optical fibre is 78.244 degrees\n",
+        "The critical propagation angle for optical fibre is 11.76 degrees\n",
+        "Numerical aperture for optical fibre is 0.292\n"
+       ]
+      }
+     ],
+     "prompt_number": 1
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 12.2, Page number 271"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "n1 = 1.45;    #Refractive index of fibre core\n",
+      "n2 = 1.4;     #Refractive index of fibre cladding\n",
+      "\n",
+      "#Calculation\n",
+      "NA = math.sqrt(n1**2 - n2**2);     #Numerical aperture for optical fibre\n",
+      "NA = math.ceil(NA*10**4)/10**4;     #rounding off the value of NA to 4 decimals\n",
+      "#As sin(theta_a) = sqrt(n1^2 - n2^2), solving for theta_a\n",
+      "theta_a = math.asin(math.sqrt(n1**2 - n2**2));     #Half of acceptance angle of optical fibre(rad)\n",
+      "theta_a = theta_a*57.2957795;     #Half of acceptance angle of optical fibre(degrees)\n",
+      "theta_accp = 2*theta_a;     #Acceptance angle of optical fibre(degrees)\n",
+      "theta_accp = math.ceil(theta_accp*10**2)/10**2;     #rounding off the value of theta_accp to 2 decimals\n",
+      "Delta = (n1 - n2)/n1;       #Relative refractive index difference\n",
+      "Delta = math.ceil(Delta*10**4)/10**4;     #rounding off the value of Delta to 4 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"Numerical aperture for optical fibre is\", NA\n",
+      "print \"The acceptance angle of optical fibre is\",theta_accp, \"degrees\"\n",
+      "print \"Relative refractive index difference is\", Delta\n"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Numerical aperture for optical fibre is 0.3775\n",
+        "The acceptance angle of optical fibre is 44.36 degrees\n",
+        "Relative refractive index difference is 0.0345\n"
+       ]
+      }
+     ],
+     "prompt_number": 2
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 12.3, Page number 271"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "n1 = 1.55;     #Refractive index of fibre core\n",
+      "n2 = 1.53;     #Refractive index of fibre cladding\n",
+      "n0 = 1.3;      #Refractive index of medium\n",
+      "\n",
+      "#Calculation\n",
+      "NA = math.sqrt(n1**2 - n2**2);     #Numerical aperture for optical fibre\n",
+      "NA = math.ceil(NA*10**4)/10**4;     #rounding off the value of NA to 4 decimals\n",
+      "#n0*sin(theta_a) = sqrt(n1^2 - n2^2) = NA, solving for theta_a\n",
+      "theta_a = math.asin(math.sqrt(n1**2 - n2**2)/n0);     #Half of acceptance angle of optical fibre(rad)\n",
+      "theta_a = theta_a*57.2957795;    #Half of acceptance angle of optical fibre(degrees)\n",
+      "theta_accp = 2*theta_a;     #Acceptance angle of optical fibre(degrees)\n",
+      "\n",
+      "#Result\n",
+      "print \"Numerical aperture for step index fibre is\",NA\n",
+      "print \"The acceptance angle of step index fibre is\",int(theta_accp), \"degrees\"\n"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Numerical aperture for step index fibre is 0.2482\n",
+        "The acceptance angle of step index fibre is 22 degrees\n"
+       ]
+      }
+     ],
+     "prompt_number": 5
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 12.4, Page number 271 Theoritical proof"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 12.5, Page number 272"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "alpha = 2;      #Power loss through optical fibre(dB/km)\n",
+      "P_in = 500;     #Poer input of optical fibre(micro-watt)\n",
+      "z = 10;        #Length of the optical fibre(km)\n",
+      "\n",
+      "#Calculation\n",
+      "#As alpha = 10/z*log10(P_in/P_out), solving for P_out\n",
+      "P_out = P_in/10**(alpha*z/10);      #Output power in fibre optic communication(micro-Watt)\n",
+      "\n",
+      "#Result\n",
+      "print \"The output power in fibre optic communication is\",P_out, \"micro-Watt\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The output power in fibre optic communication is 5.0 micro-Watt\n"
+       ]
+      }
+     ],
+     "prompt_number": 6
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": []
+    }
+   ],
+   "metadata": {}
+  }
+ ]
+}
\ No newline at end of file
diff --git a/Engineering_Physics_by_G._Aruldhas/Chapter13_1.ipynb b/Engineering_Physics_by_G._Aruldhas/Chapter13_1.ipynb
new file mode 100755
index 00000000..06b2e844
--- /dev/null
+++ b/Engineering_Physics_by_G._Aruldhas/Chapter13_1.ipynb
@@ -0,0 +1,341 @@
+{
+ "metadata": {
+  "name": "",
+  "signature": "sha256:23fe0a698ddd73a9b73b082e06aebc62f797877523bf19c5324fc5a8330a2aa8"
+ },
+ "nbformat": 3,
+ "nbformat_minor": 0,
+ "worksheets": [
+  {
+   "cells": [
+    {
+     "cell_type": "heading",
+     "level": 1,
+     "metadata": {},
+     "source": [
+      "13: Dielectric Properties of Materials"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 13.1, Page number 287"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "epsilon_0 = 8.85*10**-12;    #Absolute electrical permittivity of free space(F/m)\n",
+      "R = 0.52;       #Radius of hydrogen atom(A)\n",
+      "n = 9.7*10**26;      #Number density of hydrogen(per metre cube)\n",
+      "\n",
+      "#Calculation\n",
+      "R = R*10**-10;       #Radius of hydrogen atom(m)\n",
+      "alpha_e = 4*math.pi*epsilon_0*R**3;      #Electronic polarizability of hydrogen atom(Fm**2)\n",
+      "\n",
+      "#Result\n",
+      "print \"The electronic polarizability of hydrogen atom is\", alpha_e, \"Fm**2\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The electronic polarizability of hydrogen atom is 1.56373503182e-41 Fm**2\n"
+       ]
+      }
+     ],
+     "prompt_number": 1
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 13.2, Page number 287"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "epsilon_0 = 8.854*10**-12;    #Absolute electrical permittivity of free space(F/m)\n",
+      "A = 100;      #Area of a plate of parallel plate capacitor(cm**2)\n",
+      "d = 1;     #Distance between the plates of the capacitor(cm)\n",
+      "V = 100;    #Potential applied to the plates of the capacitor(V)\n",
+      "\n",
+      "#Calculation\n",
+      "A= A*10**-4;     #Area of a plate of parallel plate capacitor(m**2)\n",
+      "d = d*10**-2;     #Distance between the plates of the capacitor(m)\n",
+      "C = epsilon_0*A/d;     #Capacitance of parallel plate capacitor(F)\n",
+      "Q = C*V;      #Charge on the plates of the capacitor(C)\n",
+      "\n",
+      "#Result\n",
+      "print \"The capacitance of parallel plate capacitor is\",C, \"F\"\n",
+      "print \"The charge on the plates of the capacitor is\",Q, \"C\"\n"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The capacitance of parallel plate capacitor is 8.854e-12 F\n",
+        "The charge on the plates of the capacitor is 8.854e-10 C\n"
+       ]
+      }
+     ],
+     "prompt_number": 2
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 13.3, Page number 288"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "epsilon_0 = 8.854*10**-12;     #Absolute electrical permittivity of free space(F/m)\n",
+      "epsilon_r = 5.0;     #Dielectric constant of the material between the plates of capacitor\n",
+      "V = 15;      #Potential difference applied between the plates of the capacitor(V)\n",
+      "d = 1.5;     #Separation between the plates of the capacitor(mm)\n",
+      "\n",
+      "#Calculation\n",
+      "d = d*10**-3;      #Separation between the plates of the capacitor(m)\n",
+      "#Electric displacement, D = epsilon_0*epsilon_r*E, as E = V/d, so \n",
+      "D = epsilon_0*epsilon_r*V/d;      #Dielectric displacement(C/m**2)\n",
+      "\n",
+      "#Result\n",
+      "print \"The dielectric displacement is\",D, \"C/m**2\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The dielectric displacement is 4.427e-07 C/m**2\n"
+       ]
+      }
+     ],
+     "prompt_number": 3
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 13.4, Page number 288"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "epsilon_0 = 8.854*10**-12;      #Absolute electrical permittivity of free space(F/m)\n",
+      "N = 3*10**28;       #Number density of solid elemental dielectric(atoms/metre cube)\n",
+      "alpha_e = 10**-40;      #Electronic polarizability(Fm**2)\n",
+      "\n",
+      "#Calculation\n",
+      "epsilon_r = 1 + (N*alpha_e/epsilon_0);      #Relative dielectric constant of the material\n",
+      "epsilon_r = math.ceil(epsilon_r*10**3)/10**3;     #rounding off the value of epsilon_r to 3 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The Relative dielectric constant of the material is\",epsilon_r\n"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The Relative dielectric constant of the material is 1.339\n"
+       ]
+      }
+     ],
+     "prompt_number": 5
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 13.5, Page number 288"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "N_A = 6.02*10**23;     #Avogadro's number(per mole)\n",
+      "epsilon_0 = 8.854*10**-12;     #Absolute electrical permittivity of free space(F/m)\n",
+      "epsilon_r = 3.75;      #Relative dielectric constant\n",
+      "d = 2050;      #Density of sulphur(kg/metre cube)\n",
+      "y = 1/3;      #Internal field constant\n",
+      "M = 32;      #Atomic weight of sulphur(g/mol)\n",
+      "\n",
+      "#Calculation\n",
+      "N = N_A*10**3*d/M;      #Number density of atoms of sulphur(per metre cube)\n",
+      "#Lorentz relation for local fields give E_local = E + P/(3*epsilon_0) which gives\n",
+      "#(epsilon_r - 1)/(epsilon_r + 2) = N*alpha_e/(3*epsilon_0), solving for alpha_e\n",
+      "alpha_e = (epsilon_r - 1)/(epsilon_r + 2)*3*epsilon_0/N;      #Electronic polarizability of sulphur(Fm**2)\n",
+      "\n",
+      "#Result\n",
+      "print \"The electronic polarizability of sulphur is\",alpha_e, \"Fm**2\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The electronic polarizability of sulphur is 3.2940125351e-40 Fm**2\n"
+       ]
+      }
+     ],
+     "prompt_number": 6
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 13.6, Page number 289"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "N = 3*10**28;      #Number density of atoms of dielectric material(per metre cube)\n",
+      "epsilon_0 = 8.854*10**-12;     #Absolute electrical permittivity of free space(F/m)\n",
+      "n = 1.6;     #Refractive index of dielectric material\n",
+      "\n",
+      "#Calculation\n",
+      "#As (n^2 - 1)/(n^2 + 2) = N*alpha_e/(3*epsilon_0), solving for alpha_e\n",
+      "alpha_e = (n**2 - 1)/(n**2 + 2)*3*epsilon_0/N;      #Electronic polarizability of dielectric material(Fm**2)\n",
+      "\n",
+      "#Result\n",
+      "print \"The electronic polarizability of dielectric material is\",alpha_e, \"Fm**2\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The electronic polarizability of dielectric material is 3.029e-40 Fm**2\n"
+       ]
+      }
+     ],
+     "prompt_number": 8
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 13.7, Page number 289"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "epsilon_r = 4.9;       #Absolute relative dielectric constant of material(F/m)\n",
+      "n = 1.6;       #Refractive index of dielectric material\n",
+      "\n",
+      "#Calculation\n",
+      "#As (n^2 - 1)/(n^2 + 2)*(alpha_e + alpha_i)/alpha_e = N*(alpha_e + alpha_i)/(3*epsilon_0) = (epsilon_r - 1)/(epsilon_r + 2)\n",
+      "#let alpha_ratio = alpha_i/alpha_e\n",
+      "alpha_ratio = ((epsilon_r - 1)/(epsilon_r + 2)*(n**2 + 2)/(n**2 - 1) - 1)**(-1);  #Ratio of electronic polarizability to ionic polarizability\n",
+      "alpha_ratio = math.ceil(alpha_ratio*10**3)/10**3;     #rounding off the value of alpha_ratio to 3 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The ratio of electronic polarizability to ionic polarizability is\",alpha_ratio"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The ratio of electronic polarizability to ionic polarizability is 1.534\n"
+       ]
+      }
+     ],
+     "prompt_number": 9
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": []
+    }
+   ],
+   "metadata": {}
+  }
+ ]
+}
\ No newline at end of file
diff --git a/Engineering_Physics_by_G._Aruldhas/Chapter14_1.ipynb b/Engineering_Physics_by_G._Aruldhas/Chapter14_1.ipynb
new file mode 100755
index 00000000..63e03042
--- /dev/null
+++ b/Engineering_Physics_by_G._Aruldhas/Chapter14_1.ipynb
@@ -0,0 +1,365 @@
+{
+ "metadata": {
+  "name": "",
+  "signature": "sha256:396480b86092e159711151589922125e5821f00167a65ea8819e3cd4725bf191"
+ },
+ "nbformat": 3,
+ "nbformat_minor": 0,
+ "worksheets": [
+  {
+   "cells": [
+    {
+     "cell_type": "heading",
+     "level": 1,
+     "metadata": {},
+     "source": [
+      "14: Magnetic Properties of Materials"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 14.1, Page number 306"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "N = 6.02*10**23;      #Avogadro's number(per mole)\n",
+      "A = 56;      #Atomic weight of the substance(g/mole)\n",
+      "d = 7.9;     #Density of the substance(g/cm**3)\n",
+      "m_B = 9.27*10**-24;     #Bohr's Magneton(J/T)\n",
+      "\n",
+      "#Calculation\n",
+      "m = 2.2*m_B;       #Magnetic moment of substance(J/T)\n",
+      "n = d*N/A ;      #Number of atoms per unit volume of the substance(per cm**3)\n",
+      "n = n*10**6;     #Number of atoms per unit volume of the substance(per m**3)\n",
+      "M = n*m;         #Spontaneous magnetisation of the substance(A/m)\n",
+      "M = M/10**6;\n",
+      "M = math.ceil(M*10**3)/10**3;     #rounding off the value of M to 3 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The spontaneous magnetisation of the substance is\",M,\"*10**6 A/m\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The spontaneous magnetisation of the substance is 1.732 *10**6 A/m\n"
+       ]
+      }
+     ],
+     "prompt_number": 5
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 14.2, Page number 307"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "H = 200;        #Field strength to which the ferromagnetic material is subjected(A/m)\n",
+      "M = 3100;       #Magnetisation of the ferromagnetic material(A/m)\n",
+      "\n",
+      "#Calculation\n",
+      "chi = M/H;      #Magnetic susceptibility\n",
+      "mew_r = 1 + chi;    #Relative permeability of ferromagnetic material\n",
+      "\n",
+      "#Result\n",
+      "print \"The relative permeability of ferromagnetic material is\",mew_r"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The relative permeability of ferromagnetic material is 16.5\n"
+       ]
+      }
+     ],
+     "prompt_number": 6
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 14.3, Page number 307"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "H = 300;        #Field strength to which the ferromagnetic material is subjected(A/m)\n",
+      "M = 4400;       #Magnetisation of the ferromagnetic material(A/m)\n",
+      "\n",
+      "#Calculation\n",
+      "chi = M/H;      #Magnetic susceptibility\n",
+      "mew_r = 1 + chi;    #Relative permeability of ferromagnetic material\n",
+      "mew_r = math.ceil(mew_r*100)/100;     #rounding off the value of mew_r to 2 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The relative permeability of ferromagnetic material is\",mew_r\n"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The relative permeability of ferromagnetic material is 15.67\n"
+       ]
+      }
+     ],
+     "prompt_number": 7
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 14.4, Page number 307"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "mew_0 = 4*math.pi*10**-7;       #Magnetic permeability of free space(Tm/A)\n",
+      "H = 10000;         #Field strength to which the diamagnetic material is subjected(A/m)\n",
+      "chi = -0.4*10**-5;       #Magnetic susceptibility\n",
+      "\n",
+      "#Calculation\n",
+      "M = chi*H;        #Magnetisation of the diamagnetic material(A/m)\n",
+      "B = mew_0*(H + M);      #Magnetic flux density of diamagnetic material(T)\n",
+      "B = math.ceil(B*10**4)/10**4;     #rounding off the value of B to 4 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The magnetisation of diamagnetic material is\",M, \"A/m\"\n",
+      "print \"The magnetic flux density of diamagnetic material is\",B, \"T\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The magnetisation of diamagnetic material is -0.04 A/m\n",
+        "The magnetic flux density of diamagnetic material is 0.0126 T\n"
+       ]
+      }
+     ],
+     "prompt_number": 8
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 14.5, Page number 307"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "mew_0 = 4*math.pi*10**-7;      #Magnetic permeability of free space(Tm/A)\n",
+      "H = 1.2*10**5;      #Field strength to which the diamagnetic material is subjected(A/m)\n",
+      "chi = -4.2*10**-6;      #Magnetic susceptibility\n",
+      "\n",
+      "#Calculation\n",
+      "M = chi*H;      #Magnetisation of the diamagnetic material(A/m)\n",
+      "B = mew_0*(H + M);     #Magnetic flux density of diamagnetic material(T)\n",
+      "B = math.ceil(B*10**3)/10**3;     #rounding off the value of B to 3 decimals\n",
+      "mew_r = M/H + 1;       #The relative permeability of diamagnetic material\n",
+      "mew_r = math.ceil(mew_r*10**6)/10**6;     #rounding off the value of mew_r to 6 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The magnetisation of diamagnetic material is\",M, \"A/m\"\n",
+      "print \"The magnetic flux density of diamagnetic material is\",B, \"T\"\n",
+      "print \"The relative permeability of diamagnetic material is\",mew_r\n"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The magnetisation of diamagnetic material is -0.504 A/m\n",
+        "The magnetic flux density of diamagnetic material is 0.151 T\n",
+        "The relative permeability of diamagnetic material is 0.999996\n"
+       ]
+      }
+     ],
+     "prompt_number": 10
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 14.6, Page number 308"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "chi = 5.6*10**-6;      #Magnetic susceptibility of diamagnetic material\n",
+      "m = 9.1*10**-31;      #Mass of an electron(kg)\n",
+      "mew_0 = 4*math.pi*10**-7;      #Magnetic permeability of free space(Tm/A)\n",
+      "Z = 1;      #Atomic number\n",
+      "e = 1.6*10**-19;     #Electronic charge(C)\n",
+      "a = 2.53;     #Lattice parameter of bcc structure(A)\n",
+      "\n",
+      "#Calculation\n",
+      "a = a*10**-10;    #Lattice parameter of bcc structure(m)\n",
+      "N = 2/a**3;       #The number of electrons per unit volume(per metre cube)\n",
+      "r = math.sqrt(chi*6*m/(mew_0*Z*e**2*N));    #Mean radius of body centered cubic structure(m)\n",
+      "r = r*10**10;      #Mean radius of body centered cubic structure(A)\n",
+      "r = math.ceil(r*100)/100;     #rounding off the value of r to 2 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The mean radius of body centered cubic structure is\",r, \"A\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The mean radius of body centered cubic structure is 0.88 A\n"
+       ]
+      }
+     ],
+     "prompt_number": 11
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 14.7, Page number 308"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "mew_0 = 4*math.pi*10**-7;     #Magnetic permeability of free space(Tm/A)\n",
+      "N_A = 6.02*10**26;       #Avogadro's number(per kmol)\n",
+      "rho = 4370;       #Density of paramegnetic salt(kg/metre cube)\n",
+      "M = 168.5;      #Molecular weight of paramagnetic salt(g/mol)\n",
+      "T = 27;     #Temperature of paramagnetic salt(C)\n",
+      "H = 2*10**5;     #Field strength to which the  paramagnetic salt is subjected(A/m)\n",
+      "mew_B = 9.27*10**-24;      #Bohr's magneton(Am**2)\n",
+      "p = 2;          #Number of Bohr magnetons per molecule\n",
+      "k = 1.38*10**-23;      #Boltzmann constant(J/K)\n",
+      "\n",
+      "#Calculation\n",
+      "T = T+273;     #Temperature of paramagnetic salt(K)\n",
+      "N = rho*N_A/M;       #Total density of atoms in the paramagnetic salt(per meter cube)\n",
+      "chi_para = mew_0*N*p**2*mew_B**2/(3*k*T);      #Magnetic susceptibility of paramagnetic salt\n",
+      "chi_para = chi_para*10**4;\n",
+      "chi_para = math.ceil(chi_para*10**2)/10**2;     #rounding off the value of chi_para to 2 decimals\n",
+      "M = chi*H;       #Magnetisation of paramagnetic salt(A/m)\n",
+      "M = math.ceil(M*10)/10;     #rounding off the value of M to 1 decimal\n",
+      "\n",
+      "#Result\n",
+      "print \"The magnetic susceptibility of paramagnetic salt is\",chi_para,\"*10**-4\"\n",
+      "print \"The magnetisation of paramagnetic salt is\",M, \"A/m\"\n",
+      "\n",
+      "#answer for magnetisation is not given in the textbook"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The magnetic susceptibility of paramagnetic salt is 5.43 *10**-4\n",
+        "The magnetisation of paramagnetic salt is 1.2 A/m\n"
+       ]
+      }
+     ],
+     "prompt_number": 14
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": []
+    }
+   ],
+   "metadata": {}
+  }
+ ]
+}
\ No newline at end of file
diff --git a/Engineering_Physics_by_G._Aruldhas/Chapter15_1.ipynb b/Engineering_Physics_by_G._Aruldhas/Chapter15_1.ipynb
new file mode 100755
index 00000000..7bc435f1
--- /dev/null
+++ b/Engineering_Physics_by_G._Aruldhas/Chapter15_1.ipynb
@@ -0,0 +1,309 @@
+{
+ "metadata": {
+  "name": "",
+  "signature": "sha256:2292e5def6e87e01b63e6b748e8fe3955bb5676e5121c51dac319cd9531c4833"
+ },
+ "nbformat": 3,
+ "nbformat_minor": 0,
+ "worksheets": [
+  {
+   "cells": [
+    {
+     "cell_type": "heading",
+     "level": 1,
+     "metadata": {},
+     "source": [
+      "15: Thermal Properties "
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 15.1, Page number 323"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "k = 1.38*10**-23;      #Boltzmann constant(J/K)\n",
+      "h = 6.626*10**-34;      #Planck's constant(Js)\n",
+      "f_D = 64*10**11;         #Debye frequency for Al(Hz)\n",
+      "\n",
+      "#Calculation\n",
+      "theta_D = h*f_D/k;     #Debye temperature(K)\n",
+      "theta_D = math.ceil(theta_D*10)/10;     #rounding off the value of theta_D to 1 decimal\n",
+      "\n",
+      "#Result\n",
+      "print \"The Debye temperature of aluminium is\",theta_D, \"K\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The Debye temperature of aluminium is 307.3 K\n"
+       ]
+      }
+     ],
+     "prompt_number": 2
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 15.2, Page number 323"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "N = 6.02*10**26;    #Avogadro's number(per kmol)\n",
+      "k = 1.38*10**-23;    #Boltzmann constant(J/K)\n",
+      "h = 6.626*10**-34;    #Planck's constant(Js)\n",
+      "f_D = 40.5*10**12;     #Debye frequency for Al(Hz)\n",
+      "T = 30;        #Temperature of carbon(Ks)\n",
+      "\n",
+      "#Calculation\n",
+      "theta_D = h*f_D/k;      #Debye temperature(K)\n",
+      "C_l = 12/5*math.pi**4*N*k*(T/theta_D)**3;       #Lattice specific heat of carbon(J/k-mol/K)\n",
+      "C_l = math.ceil(C_l*10**3)/10**3;     #rounding off the value of C_l to 3 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The lattice specific heat of carbon is\",C_l, \"J/k-mol/K\"\n",
+      "\n",
+      "#answer given in the book is wrong in the 2nd decimal"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The lattice specific heat of carbon is 7.132 J/k-mol/K\n"
+       ]
+      }
+     ],
+     "prompt_number": 3
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 15.3, Page number 323"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "k = 1.38*10**-23;       #Boltzmann constant(J/K)\n",
+      "h = 6.626*10**-34;      #Planck's constant(Js)\n",
+      "theta_E = 1990;        #Einstein temperature of Cu(K)\n",
+      "\n",
+      "#Calculation\n",
+      "f_E = k*theta_E/h;     #Einstein frequency for Cu(K)\n",
+      "\n",
+      "#Result\n",
+      "print \"The Einstein frequency for Cu is\",f_E, \"Hz\"\n",
+      "print \"The frequency falls in the near infrared region\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The Einstein frequency for Cu is 4.14458194989e+13 Hz\n",
+        "The frequency falls in the near infrared region\n"
+       ]
+      }
+     ],
+     "prompt_number": 4
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 15.4, Page number 323"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "e = 1.6*10**-19;     #Energy equivalent of 1 eV(J/eV)\n",
+      "N = 6.02*10**23;      #Avogadro's number(per mol)\n",
+      "T = 0.05;       #Temperature of Cu(K)\n",
+      "E_F = 7;       #Fermi energy of Cu(eV)\n",
+      "k = 1.38*10**-23;     #Boltzmann constant(J/K)\n",
+      "h = 6.626*10**-34;     #Planck's constant(Js)\n",
+      "theta_D = 348;      #Debye temperature of Cu(K)\n",
+      "\n",
+      "#Calculation\n",
+      "C_e = math.pi**2*N*k**2*T/(2*E_F*e);     #Electronic heat capacity of Cu(J/mol/K)\n",
+      "C_V = (12/5)*math.pi**4*(N*k)*(T/theta_D)**3;      #Lattice heat capacity of Cu(J/mol/K)\n",
+      "\n",
+      "#Result\n",
+      "print \"The electronic heat capacity of Cu is\",C_e, \"J/mol/K\"\n",
+      "print \"The lattice heat capacity of Cu is\",C_V, \"J/mol/K\"\n",
+      "\n",
+      "#answer for lattice heat capacity given in the book is wrong"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The electronic heat capacity of Cu is 2.52566877726e-05 J/mol/K\n",
+        "The lattice heat capacity of Cu is 5.76047891492e-09 J/mol/K\n"
+       ]
+      }
+     ],
+     "prompt_number": 5
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 15.5, Page number 324"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "T = 1;      #For simplicity assume temperature to be unity(K)\n",
+      "R = 1;      #For simplicity assume molar gas constant to be unity(J/mol/K)\n",
+      "theta_E = T;    #Einstein temperature(K)\n",
+      "\n",
+      "#Calculation\n",
+      "C_V = 3*R*(theta_E/T)**2*math.exp(theta_E/T)/(math.exp(theta_E/T)-1)**2;    #Einstein lattice specific heat(J/mol/K)\n",
+      "C_V = C_V/3;\n",
+      "C_V = math.ceil(C_V*10**3)/10**3;     #rounding off the value of C_V to 3 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The Einstein lattice specific heat is\",C_V, \"X 3R\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The Einstein lattice specific heat is 0.921 X 3R\n"
+       ]
+      }
+     ],
+     "prompt_number": 6
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 15.6, Page number 324"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "e = 1.6*10**-19;      #Energy equivalent of 1 eV(J/eV)\n",
+      "v = 2;     #Valency of Zn atom\n",
+      "N = v*6.02*10**23;      #Avogadro's number(per mol)\n",
+      "T = 300;     #Temperature of Zn(K)\n",
+      "E_F = 9.38;     #Fermi energy of Zn(eV)\n",
+      "k = 1.38*10**-23;    #Boltzmann constant(J/K)\n",
+      "h = 6.626*10**-34;    #Planck's constant(Js)\n",
+      "\n",
+      "#Calculation\n",
+      "N = v*6.02*10**23;      #Avogadro's number(per mol)\n",
+      "C_e = math.pi**2*N*k**2*T/(2*E_F*e);    #Electronic heat capacity of Zn(J/mol/K)\n",
+      "C_e = math.ceil(C_e*10**4)/10**4;     #rounding off the value of C_e to 4 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The molar electronic heat capacity of zinc is\",C_e, \"J/mol/K\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The molar electronic heat capacity of zinc is 0.2262 J/mol/K\n"
+       ]
+      }
+     ],
+     "prompt_number": 8
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": []
+    }
+   ],
+   "metadata": {}
+  }
+ ]
+}
\ No newline at end of file
diff --git a/Engineering_Physics_by_G._Aruldhas/Chapter17_1.ipynb b/Engineering_Physics_by_G._Aruldhas/Chapter17_1.ipynb
new file mode 100755
index 00000000..891f2d43
--- /dev/null
+++ b/Engineering_Physics_by_G._Aruldhas/Chapter17_1.ipynb
@@ -0,0 +1,76 @@
+{
+ "metadata": {
+  "name": "",
+  "signature": "sha256:d4400dbe9ddae05e5ab81173c9df50e2e9dde25edf961941bd9c8dc15f5a6fe1"
+ },
+ "nbformat": 3,
+ "nbformat_minor": 0,
+ "worksheets": [
+  {
+   "cells": [
+    {
+     "cell_type": "heading",
+     "level": 1,
+     "metadata": {},
+     "source": [
+      "17: Ultrasonics"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 17.1, Page number 352"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "f = 3;        #Fundamental vibrational frequency of quartz crystal(MHz)\n",
+      "Y = 7.9*10**10;       #Young's modulus of quartz(N/m**2)\n",
+      "rho = 2650;      #Density of quartz(kg/m**3)\n",
+      "\n",
+      "#Calculation\n",
+      "f = f*10**6;    #Fundamental vibrational frequency of quartz crystal(Hz)\n",
+      "l = 1/(2*f)*math.sqrt(Y/rho);    #Thickness of vibrating quartz at resonance(m)\n",
+      "l = l*10**3;       #Thickness of vibrating quartz at resonance(mm)\n",
+      "l = math.ceil(l*100)/100;     #rounding off the value of l to 2 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The thickness of vibrating quartz at resonance is\",l, \"mm\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The thickness of vibrating quartz at resonance is 0.91 mm\n"
+       ]
+      }
+     ],
+     "prompt_number": 1
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": []
+    }
+   ],
+   "metadata": {}
+  }
+ ]
+}
\ No newline at end of file
diff --git a/Engineering_Physics_by_G._Aruldhas/Chapter18_1.ipynb b/Engineering_Physics_by_G._Aruldhas/Chapter18_1.ipynb
new file mode 100755
index 00000000..553fe50f
--- /dev/null
+++ b/Engineering_Physics_by_G._Aruldhas/Chapter18_1.ipynb
@@ -0,0 +1,300 @@
+{
+ "metadata": {
+  "name": "",
+  "signature": "sha256:c2afbaf4a700c8f5f48d1946053d882d86bb1b0270a68b2bbedc639668ea43be"
+ },
+ "nbformat": 3,
+ "nbformat_minor": 0,
+ "worksheets": [
+  {
+   "cells": [
+    {
+     "cell_type": "heading",
+     "level": 1,
+     "metadata": {},
+     "source": [
+      "18: Acoustics of Buildings"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 18.1, Page number 361"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "r = 200;       #Distance of the point of reduction from the source(m)\n",
+      "I_0 = 10**-12;    #Final intensity of sound(W/m**2)\n",
+      "I_f = 60;        #Intensity gain of sound at the point of reduction(dB)\n",
+      "\n",
+      "#Calculation\n",
+      "#As A_I = 10*log10(I/I_0), solving for I\n",
+      "I = I_0*10**(I_f/10);      #Initial Intensity of sound(W/m**2)\n",
+      "P = 4*math.pi*r**2*I;      #Output power of the sound source(W)\n",
+      "P = math.ceil(P*100)/100;     #rounding off the value of P to 2 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The output power of the sound source is\",P, \"W\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The output power of the sound source is 0.51 W\n"
+       ]
+      }
+     ],
+     "prompt_number": 1
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 18.2, Page number 361"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "import numpy as np\n",
+      "\n",
+      "#Variable declaration\n",
+      "I1 = 1;    #For simplicity assume first intensity level to be unity(W/m**2)\n",
+      "\n",
+      "#Calculation\n",
+      "I2 = 2*I1;    #Intensity level after doubling(W/m**2)\n",
+      "dA_I = 10*np.log10(I2/I1);    #Difference in gain level(dB)\n",
+      "\n",
+      "#Result\n",
+      "print \"The sound intensity level is increased by\",int(dA_I), \"dB\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The sound intensity level is increased by 3 dB\n"
+       ]
+      }
+     ],
+     "prompt_number": 3
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 18.3, Page number 361"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "V = 8000;    #Volume of the hall(m**3)\n",
+      "T = 1.5;     #Reverbration time of the hall(s)\n",
+      "\n",
+      "#Calculation\n",
+      "alpha_s = 0.167*V/T;     #Sabine Formula giving total absorption of sound in the hall(OWU)\n",
+      "alpha_s = math.ceil(alpha_s*10)/10;     #rounding off the value of alpha_s to 1 decimal\n",
+      "\n",
+      "#Result\n",
+      "print \"The total absorption of sound in the hall is\",alpha_s, \"OWU\"\n"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The total absorption of sound in the hall is 890.7 OWU\n"
+       ]
+      }
+     ],
+     "prompt_number": 4
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 18.4, Page number 362"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "V = 25*20*8;       #Volume of the hall(m**3)\n",
+      "T = 4;     #Reverbration time of the hall(s)\n",
+      "\n",
+      "#Calculation\n",
+      "S = 2*(25*20+25*8+20*8);    #Total surface area of the hall(m**2)\n",
+      "alpha = 0.167*V/(T*S);     #Sabine Formule giving total absorption in the hall(OWU)\n",
+      "alpha = math.ceil(alpha*10**4)/10**4;     #rounding off the value of alpha to 4 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The average absorption coefficient of the surfaces is\",alpha, \"OWU/m**2\"\n"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The average absorption coefficient of the surfaces is 0.0971 OWU/m**2\n"
+       ]
+      }
+     ],
+     "prompt_number": 5
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 18.5, Page number 362"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "V = 475;      #Volume of the hall(m**3)\n",
+      "A_f = 100;     #Area of the floor(m**2)\n",
+      "A_c = 100;     #Area of the ceiling(m**2)\n",
+      "A_w = 200;     #Area of the wall(m**2)\n",
+      "alpha_w = 0.025;     #Absorption coefficients of the wall(OWU/m**2)\n",
+      "alpha_c = 0.02;      #Absorption coefficients of the ceiling(OWU/m**2)\n",
+      "alpha_f = 0.55;      #Absorption coefficients of the floor(OWU/m**2)\n",
+      "\n",
+      "#Calculation\n",
+      "alpha_s = (A_w*alpha_w)+(A_c*alpha_c)+(A_f*alpha_f);    \n",
+      "T = 0.167*V/alpha_s;    #Sabine Formula for reverbration time(s)\n",
+      "T = math.ceil(T*100)/100;     #rounding off the value of T to 2 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The reverbration time for the hall is\",T, \"s\"\n"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The reverbration time for the hall is 1.28 s\n"
+       ]
+      }
+     ],
+     "prompt_number": 6
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 18.6, Page number 362"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "I0 = 1;    #For simplicity assume initial sound intensity to be unity(W/m**2)\n",
+      "A_I1 = 80;   #First intensity gain of sound(dB)\n",
+      "A_I2 = 70;   #Second intensity gain of sound(dB)\n",
+      "\n",
+      "#Calculation\n",
+      "#As A_I = 10*log10(I/I_0), solving for I1 and I2\n",
+      "I1 = 10**(A_I1/10)*I0;    #First intensity of sound(W/m**2)\n",
+      "I2 = 10**(A_I2/10)*I0;    #Second intensity of sound(W/m**2)\n",
+      "I = I1 + I2;     #Resultant intensity level of sound(W/m**2)\n",
+      "A_I = 10*np.log10(I/I0);    #Intensity gain of resultant sound(dB)\n",
+      "A_I = math.ceil(A_I*10**3)/10**3;     #rounding off the value of A_I to 3 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The intensity gain of resultant sound is\",A_I, \"dB\"\n",
+      "\n",
+      "#answer given in the book is wrong"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The intensity gain of resultant sound is 80.414 dB\n"
+       ]
+      }
+     ],
+     "prompt_number": 7
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": []
+    }
+   ],
+   "metadata": {}
+  }
+ ]
+}
\ No newline at end of file
diff --git a/Engineering_Physics_by_G._Aruldhas/Chapter1_1.ipynb b/Engineering_Physics_by_G._Aruldhas/Chapter1_1.ipynb
new file mode 100755
index 00000000..7872d7ab
--- /dev/null
+++ b/Engineering_Physics_by_G._Aruldhas/Chapter1_1.ipynb
@@ -0,0 +1,475 @@
+{
+ "metadata": {
+  "name": "",
+  "signature": "sha256:381979e560591138195a6149a5aa889c9c7e2cfe41c7a482a0ea4bbe4c24f150"
+ },
+ "nbformat": 3,
+ "nbformat_minor": 0,
+ "worksheets": [
+  {
+   "cells": [
+    {
+     "cell_type": "heading",
+     "level": 1,
+     "metadata": {},
+     "source": [
+      "1: Oscillations and Waves"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 1.1, Page number 23"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#import modules\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "S=4;    #SHM described by a particle(cm)\n",
+      "x=0;    #mean position\n",
+      "v=12;   #velocity at mean position(cm/s)\n",
+      "\n",
+      "#Calculation\n",
+      "A=S/2;    #amplitude of motion(cm)\n",
+      "omega=v/A;    #angular frequency(sec-1)\n",
+      "T=(2*math.pi)/omega;    #time period(sec)\n",
+      "T=math.ceil(T*10**3)/10**3;   #rounding off to 3 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"time period of motion is\",T, \"sec\"\n",
+      "print \"time period of motion is pi/3 sec\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "time period of motion is 1.048 sec\n",
+        "time period of motion is pi/3 sec\n"
+       ]
+      }
+     ],
+     "prompt_number": 2
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 1.2, Page number 23"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#import modules\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "T=0.1;    #time period(sec)\n",
+      "A=4;    #amplitude of motion(cm)\n",
+      "x=0.2;    #distance from mean position(cm)\n",
+      "\n",
+      "#Calculation\n",
+      "omega=(2*math.pi)/T;    #angular frequency(sec-1)\n",
+      "a=(omega**2)*x;     #acceleration(cm/sec^2)\n",
+      "a=math.ceil(a*10**2)/10**2;   #rounding off to 2 decimals\n",
+      "#maximum velocity is when particle is in the mean position\n",
+      "v_max=omega*A;    #maximum velocity(cm/sec)\n",
+      "v_max=math.ceil(v_max*10**2)/10**2;   #rounding off to 2 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"acceleration is\",a, \"cm/sec^2\"\n",
+      "print \"maximum velocity is\",v_max, \"cm/sec\"\n",
+      "\n",
+      "#answers given in the book are wrong"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "acceleration is 789.57 cm/sec^2\n",
+        "maximum velocity is 251.33 cm/sec\n"
+       ]
+      }
+     ],
+     "prompt_number": 3
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 1.3, Page number 24"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#import modules\n",
+      "import math\n",
+      "import numpy as np\n",
+      "\n",
+      "#Variable declaration\n",
+      "A1 = 40;    #First amplitude of oscillation(cm)\n",
+      "An_plus_1 = 4;    #Amplitude after 100 oscillations(cm)\n",
+      "n = 100;    #Number of oscillations\n",
+      "T = 2.5;    #Time period of oscillations(s)\n",
+      "\n",
+      "#Calculation\n",
+      "t = T/4;    #Time taken to reach the first amplitude from the mean position(s)\n",
+      "#Now A1 = x0*math.exp(-lambda*t) and An_plus_1 = x0*math.exp(-lambda*(t+nT))\n",
+      "#A1/An_plus_1 = math.exp(n*lambda*T)\n",
+      "x=A1/An_plus_1;\n",
+      "lamda=np.log(x)/(n*T);    #Damping constant(per sec)\n",
+      "lamda=lamda*10**2;\n",
+      "lamda=math.ceil(lamda*10**3)/10**3;   #rounding off to 3 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"Damping constant is\",lamda,\"*10**-2 per sec\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Damping constant is 0.922 *10**-2 per sec\n"
+       ]
+      }
+     ],
+     "prompt_number": 6
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 1.4, Page number 24"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#import modules\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "x1 = 3;    #First position of the particle(cm)\n",
+      "x2 = 4;    #Second position of the particle(cm)\n",
+      "v1 = 16;   #Velocity of particle executing SHM at 1st position(cm/s)\n",
+      "v2 = 12;   #Velocity of particle executing SHM at 2nd position (cm/s)\n",
+      "\n",
+      "#Calculation\n",
+      "#As v = omega*sqrt(A**2 - x**2) so\n",
+      "#(v1/v2)**2=(A**2 - x1**2)/(A**2 - x2**2)\n",
+      "#RHS gives (A**2-9)/(A**2-16)\n",
+      "#(v2**2)*(A**2 - x1**2)=(v1**2)*(A**2 - x2**2), on solving we get\n",
+      "A=math.sqrt((((v1**2)*(x2**2))-((v2**2)*(x1**2)))/((v1**2)-(v2**2)));    #amplitude in cm\n",
+      "omega=v1/math.sqrt(A**2-x1**2);    #Angular speed of the particle(per sec)\n",
+      "T=2*math.pi/omega;    #Time period of oscillation(sec)\n",
+      "T=math.ceil(T*10**3)/10**3;   #rounding off to 3 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The amplitude of SHM is\",A, \"cm\"\n",
+      "print \"The time period of oscillation is\",T, \"sec\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The amplitude of SHM is 5.0 cm\n",
+        "The time period of oscillation is 1.571 sec\n"
+       ]
+      }
+     ],
+     "prompt_number": 7
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 1.5, Page number 25"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#import modules\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "m = 0.3;    #Mass attached to the string(kg)\n",
+      "g = 9.8;    #Acceleration due to gravity(m/sec**2)\n",
+      "x = 0.15;   #Stretchness produced in the spring(m)\n",
+      "s = 0.1;    #spring is stretched and released(m)\n",
+      "\n",
+      "#Calculation\n",
+      "F = m*g;    #Restoring force acting on the mass(N)\n",
+      "k = F/x;    #Spring constant(N/m)\n",
+      "A = s;     #amplitude equals to the spring stretched and released\n",
+      "omega = math.sqrt(k/m);    #Angular frequency of oscillation(rad per sec)\n",
+      "v0 = omega*A;    #Maximum velocity during the oscillations(m/s)\n",
+      "v0=math.ceil(v0*100)/100;   #rounding off to 2 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The spring constant is\",k, \"N/m\"\n",
+      "print \"The amplitude of oscillation is\",A, \"m\"\n",
+      "print \"The maximum velocity during oscillations is\",v0, \"m/s\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The spring constant is 19.6 N/m\n",
+        "The amplitude of oscillation is 0.1 m\n",
+        "The maximum velocity during oscillations is 0.81 m/s\n"
+       ]
+      }
+     ],
+     "prompt_number": 8
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 1.6, Page number 25"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#import modules\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "lambda1 = 400;    #Lower limit of wavelength of visible region(nm)\n",
+      "lambda2 = 700;    #Upper limit of wavelength of visible region(nm)\n",
+      "c = 3*10**8;    #Speed of light in vacuum(m/s)\n",
+      "\n",
+      "#Calculation\n",
+      "lambda1 = lambda1*10**-9     #Lower limit of wavelength(m) \n",
+      "lambda2 = lambda2*10**-9     #upper limit of wavelength(m) \n",
+      "new_1 = c/lambda1;    #Upper limit of frequency of visible region(m)\n",
+      "new_2 = c/lambda2;    #Lower limit of frequency of visible region(m)\n",
+      "\n",
+      "#Result\n",
+      "print \"The frequency equivalent of 400 nm is\",new_1, \"Hz\"\n",
+      "print \"The frequency equivalent of 700 nm is\",new_2, \"Hz\"\n"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The frequency equivalent of 400 nm is 7.5e+14 Hz\n",
+        "The frequency equivalent of 700 nm is 4.28571428571e+14 Hz\n"
+       ]
+      }
+     ],
+     "prompt_number": 9
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 1.7, Page number 26"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#import modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "#Comparing the standard equation u(x,t) = A*sin(2*%pi(x/lambda-t/T)) with the given equation, we get\n",
+      "A = 1.5*10**-3;    #Amplitude of the sound wave(m)\n",
+      "lamda = 8;    #Wavelength of the sound wave(m)\n",
+      "T = 1/40;     #Time period of the sound wave(s)\n",
+      "\n",
+      "#Calculation\n",
+      "A = A*10**3;\n",
+      "new = 1/T;     #Frequency of the sound wave(Hz)\n",
+      "v = new*lamda;    #Velocity of the sound wave(m/s)\n",
+      "T=math.ceil(T*100)/100;   #rounding off to 2 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The amplitude of the sound wave is\",A,\"*10**-3 m\"\n",
+      "print \"The wavelength of the sound wave is\",lamda, \"m\"\n",
+      "print \"The time period of the sound wave is\",T, \"s\"\n",
+      "print \"The frequency of the sound wave is\",new, \"Hz\"\n",
+      "print \"The velocity of the sound wave is\",v, \"m/s\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The amplitude of the sound wave is 1.5 *10**-3 m\n",
+        "The wavelength of the sound wave is 8 m\n",
+        "The time period of the sound wave is 0.03 s\n",
+        "The frequency of the sound wave is 40.0 Hz\n",
+        "The velocity of the sound wave is 320.0 m/s\n"
+       ]
+      }
+     ],
+     "prompt_number": 12
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 1.8, Page number 26"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#import modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "A = 2;    #Amplitude of the wave(cm)\n",
+      "T = 0.5;   #Time period of the wave(sec)\n",
+      "v = 200;    #Wave velocity(cm/s)\n",
+      "\n",
+      "#Calculation\n",
+      "f = 1/T;   #Frequency of the wave(Hz)\n",
+      "lamda = v/f;  #Wavelength of the wave(cm)\n",
+      "\n",
+      "#Result\n",
+      "print \"frequency of wave is\",f, \"Hz\"\n",
+      "print \"wavelength of wave is\",lamda, \"cm\"\n",
+      "print \"The Equation of the wave moving along X-axis :\"\n",
+      "print \"u = \",A,\"*sin*2*math.pi*(x/\",lamda,\"- t/\",T,\")\"     #x and y are in cm and t is in sec"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "frequency of wave is 2.0 Hz\n",
+        "wavelength of wave is 100.0 cm\n",
+        "The Equation of the wave moving along X-axis :\n",
+        "u =  2 *sin*2*math.pi*(x/ 100.0 - t/ 0.5 )\n"
+       ]
+      }
+     ],
+     "prompt_number": 13
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 1.9, Page number 27"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#import modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "T = 1000;    #Tension in the wire(N)\n",
+      "M=15;    #mass of the wire(kg)\n",
+      "l=300;   #length of the wire(m)\n",
+      "lamda = 0.30;    #Wavelength of wave along wire(m)\n",
+      "\n",
+      "#Calculation\n",
+      "m = M/l;    #Mass per unit length of the wire(kg/m)\n",
+      "v = math.sqrt(T/m);    #Velocity of wave through wire(m/s)\n",
+      "v=math.ceil(v*100)/100;   #rounding off to 2 decimals\n",
+      "new = v/lamda;    #Frequency of wave through string(Hz)\n",
+      "new=math.ceil(new*100)/100;   #rounding off to 2 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The velocity of the wave through wire is\",v, \"m/s\"\n",
+      "print \"The frequency of the wave through wire is\",new, \"Hz\"\n",
+      "\n",
+      "#answer for frequency of the wave is wrong in the textbook"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The velocity of the wave through wire is 141.43 m/s\n",
+        "The frequency of the wave through wire is 471.44 Hz\n"
+       ]
+      }
+     ],
+     "prompt_number": 15
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": []
+    }
+   ],
+   "metadata": {}
+  }
+ ]
+}
\ No newline at end of file
diff --git a/Engineering_Physics_by_G._Aruldhas/Chapter2_1.ipynb b/Engineering_Physics_by_G._Aruldhas/Chapter2_1.ipynb
new file mode 100755
index 00000000..fdbf44b5
--- /dev/null
+++ b/Engineering_Physics_by_G._Aruldhas/Chapter2_1.ipynb
@@ -0,0 +1,248 @@
+{
+ "metadata": {
+  "name": "",
+  "signature": "sha256:de195a4faed398c9714bc27769421926f24c448f7ad7f1d4cb04dd3cfbb18334"
+ },
+ "nbformat": 3,
+ "nbformat_minor": 0,
+ "worksheets": [
+  {
+   "cells": [
+    {
+     "cell_type": "heading",
+     "level": 1,
+     "metadata": {},
+     "source": [
+      "2: Electromagnetic Theory"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 2.1, Page number 46"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "from __future__ import division\n",
+      "from sympy import *\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "C = 10;    #Capacitance of the capacitor(pF)\n",
+      "#given V=0.2*sin(120*math.pi*t) in volts\n",
+      "\n",
+      "#Calculation\n",
+      "C=C*10**-12;     #Capacitance of the capacitor(F)\n",
+      "x, y, z, t = symbols('x y z t')\n",
+      "k, m, n = symbols('k m n', integer=True)\n",
+      "f, g, h = symbols('f g h', cls=Function)\n",
+      "#I = C*dV/dt\n",
+      "#let dV/dt be a\n",
+      "a=diff(0.2*sin(120*math.pi*t),t)     #dV/dt\n",
+      "#value of dV/dt is 75.398223686155*cos(376.991118430775*t)\n",
+      "#for cosine function peak value occurs when 120*math.pi*t = 0\n",
+      "#therefore value of dV/dt becomes d = 75.398223686155\n",
+      "d = 75.398223686155;    #value of dV/dt \n",
+      "I=C*d;     #displacement current(A)\n",
+      "\n",
+      "#Result\n",
+      "print \"value of dV/dt is\",a\n",
+      "print \"displacement current is\",I, \"A\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "value of dV/dt is 75.398223686155*cos(376.991118430775*t)\n",
+        "displacement current is 7.53982236862e-10 A\n"
+       ]
+      }
+     ],
+     "prompt_number": 2
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 2.2, Page number 46"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "from __future__ import division\n",
+      "from sympy import *\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "epsilon_r = 1;    #Relative electrical permittivity of free space\n",
+      "epsilon_0 = 8.854*10**-12;    #Absolute electrical permittivity of free space(F/m)\n",
+      "#given E=sin(120*math.pi*t) in volts\n",
+      "\n",
+      "#Calculation\n",
+      "x, y, z, t = symbols('x y z t')\n",
+      "k, m, n = symbols('k m n', integer=True)\n",
+      "f, g, h = symbols('f g h', cls=Function)\n",
+      "#J2 = epsilon*dE/dt\n",
+      "epsilon=epsilon_0*epsilon_r;\n",
+      "#let dE/dt be a\n",
+      "a=diff(sin(120*math.pi*t),t)     #dE/dt\n",
+      "#value of dE/dt is 376.991118430775*cos(376.991118430775*t)\n",
+      "#for cosine function peak value occurs when 120*math.pi*t = 0\n",
+      "#therefore value of dE/dt becomes d = 376.991118430775\n",
+      "d = 376.991118430775;    #value of dE/dt\n",
+      "J2=epsilon*d;     #displacement current density(A/m**2)\n",
+      "\n",
+      "#Result\n",
+      "print \"value of dE/dt is\",a\n",
+      "print \"The peak value of displacement current density is\",J2, \"A/m**2\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "value of dE/dt is 376.991118430775*cos(376.991118430775*t)\n",
+        "The peak value of displacement current density is 3.33787936259e-09 A/m**2\n"
+       ]
+      }
+     ],
+     "prompt_number": 3
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 2.3, Page number 47 (Theoritical proof)"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 2.4, Page number 47"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "from __future__ import division\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "p = 60;    #Power rating of bulb(W)\n",
+      "d = 0.5;    #Distance from the bulb(m)\n",
+      "\n",
+      "#Calculation\n",
+      "A=4*math.pi*d**2;    #area(m**2)\n",
+      "P = p/A;    #Value of Poynting vector(W/m**2)\n",
+      "P = math.ceil(P*100)/100;    #rounding off value of P to 1 decimal\n",
+      "\n",
+      "#Result\n",
+      "print \"The value of Poynting vector is\",P, \"W/m**2\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The value of Poynting vector is 19.1 W/m**2\n"
+       ]
+      }
+     ],
+     "prompt_number": 4
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 2.5, Page number 47"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#importing modules\n",
+      "from __future__ import division\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "E_peak = 6;    #Peak value of electric field intensity(V/m)\n",
+      "c = 3*10**8;    #Speed of electromagnetic wave in free space(m/s)\n",
+      "mew_0 = 4*math.pi*10**-7;    #Absolute permeability of free space(Tm/A)\n",
+      "epsilon_0 = 8.854*10**-12;    #Absolute permittivity of free space(F/m)\n",
+      "mew_r = 1;    #Relative permeability of medium\n",
+      "epsilon_r = 3;    #Relative permittivity of the medium\n",
+      "\n",
+      "#Calculation\n",
+      "v = c/math.sqrt(mew_r*epsilon_r);    #Wave velocity(m/s)\n",
+      "v = v/10**8;\n",
+      "v = math.ceil(v*10**4)/10**4;     #rounding off the value of v to 4 decimals\n",
+      "eta = math.sqrt((mew_0/epsilon_0)*(mew_r/epsilon_r));    #Intrinsic impedance of the medium(ohm)\n",
+      "eta = math.ceil(eta*10)/10;     #rounding off the value of v to 1 decimal\n",
+      "H_P = E_peak/eta;     #Peak value of the magnetic intensity(A/m)\n",
+      "H_P = H_P*10**2;\n",
+      "H_P = math.ceil(H_P*10**2)/10**2;     #rounding off the value of v to 2 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The wave velocity is\",v,\"*10**8 m/s\"\n",
+      "print \"The intrinsic impedance of the medium is\",eta, \"ohm\"\n",
+      "print \"The peak value of the magnetic intensity is\",H_P,\"*10**-2 A/m\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The wave velocity is 1.7321 *10**8 m/s\n",
+        "The intrinsic impedance of the medium is 217.6 ohm\n",
+        "The peak value of the magnetic intensity is 2.76 *10**-2 A/m\n"
+       ]
+      }
+     ],
+     "prompt_number": 11
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": []
+    }
+   ],
+   "metadata": {}
+  }
+ ]
+}
\ No newline at end of file
diff --git a/Engineering_Physics_by_G._Aruldhas/Chapter3_1.ipynb b/Engineering_Physics_by_G._Aruldhas/Chapter3_1.ipynb
new file mode 100755
index 00000000..645d7595
--- /dev/null
+++ b/Engineering_Physics_by_G._Aruldhas/Chapter3_1.ipynb
@@ -0,0 +1,476 @@
+{
+ "metadata": {
+  "name": "",
+  "signature": "sha256:bdc5e7b39dc3529751aa6372cd3db8b0870c9abab4c9b51855fb3bce7de6dc73"
+ },
+ "nbformat": 3,
+ "nbformat_minor": 0,
+ "worksheets": [
+  {
+   "cells": [
+    {
+     "cell_type": "heading",
+     "level": 1,
+     "metadata": {},
+     "source": [
+      "3: Interference"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 3.1, Page number 71"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "from __future__ import division\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "beta = 0.51;    #Fringe width(mm)\n",
+      "d = 2.2;        #Distance between the slits(mm)\n",
+      "D = 2;      #Distance between the slits and the screen(m)\n",
+      "\n",
+      "#Calculation\n",
+      "beta = beta*10**-1;     #Fringe width(cm)\n",
+      "d = d*10**-1;    #Distance between the slits(cm)\n",
+      "D=D*10**2;    #Distance between the slits and the screen(cm)\n",
+      "lamda = beta*d/D;    #Wavelength of light(cm)\n",
+      "lamda = lamda*10**8;     #Wavelength of light(A)\n",
+      "\n",
+      "#Result\n",
+      "print \"The wavelength of light is\",lamda, \"angstrom\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The wavelength of light is 5610.0 angstrom\n"
+       ]
+      }
+     ],
+     "prompt_number": 4
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 3.2, Page number 71"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "from __future__ import division\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "lambda1 = 4250;    #First wavelength emitted by source of light(A)\n",
+      "lambda2 = 5050;    #Second wavelength emitted by source of light(A)\n",
+      "D = 1.5;    #Distance between the source and the screen(m)\n",
+      "d = 0.025;       #Distance between the slits(mm)\n",
+      "n = 3;    #Number of fringe from the centre\n",
+      "\n",
+      "#Calculation\n",
+      "lambda1 = lambda1*10**-10;     #First wavelength emitted(m)\n",
+      "lambda2 = lambda2*10**-10;     #Second wavelength emitted(m)\n",
+      "d = d*10**-3;     #Distance between the slits(m)\n",
+      "x3 = n*lambda1*D/d;    #Position of third bright fringe due to lambda1(m)\n",
+      "x3_prime = n*lambda2*D/d;    #Position of third bright fringe due to lambda2(m)\n",
+      "x = x3_prime-x3;      #separation between the third bright fringe(m)\n",
+      "x = x*10**2;    #separation between the third bright fringe(cm)\n",
+      "\n",
+      "#Result\n",
+      "print \"The separation between the third bright fringe due to the two wavelengths is\",x, \"cm\"\n"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The separation between the third bright fringe due to the two wavelengths is 1.44 cm\n"
+       ]
+      }
+     ],
+     "prompt_number": 5
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 3.3, Page number 71"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "lamda = 5.5*10**-5;    #Wavelength emitted by source of light(cm)\n",
+      "n = 4;    #Number of fringes shifted\n",
+      "t = 3.9*10**-4;    #Thickness of the thin glass sheet(cm)\n",
+      "\n",
+      "#Calculation\n",
+      "mew = (n*lamda/t)+1;    #Refractive index of the sheet of glass\n",
+      "mew = math.ceil(mew*10**4)/10**4;     #rounding off the value of v to 4 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The refractive index of the sheet of glass is\",mew"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The refractive index of the sheet of glass is 1.5642\n"
+       ]
+      }
+     ],
+     "prompt_number": 6
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 3.4, Page number 72"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "lamda = 5893;    #Wavelength of monochromatic lihgt used(A)\n",
+      "n = 1;    #Number of fringe for the least thickness of the film\n",
+      "cosr = 1;    #for normal incidence\n",
+      "mew = 1.42;    #refractive index of the soap film\n",
+      "\n",
+      "#Calculation\n",
+      "#As for constructive interference, \n",
+      "#2*mew*t*cos(r) = (2*n-1)*lambda/2, solving for t\n",
+      "t = (2*n-1)*lamda/(4*mew*cosr);    #Thickness of the film that appears bright(A)\n",
+      "#As for destructive interference, \n",
+      "#2*mu*t*cos(r) = n*lambda, solving for t\n",
+      "t1 = n*lamda/(2*mew*cosr);    #Thickness of the film that appears bright(A)\n",
+      "\n",
+      "#Result\n",
+      "print \"The thickness of the film that appears bright is\",t, \"angstrom\"\n",
+      "print \"The thickness of the film that appears dark is\",t1, \"angstrom\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The thickness of the film that appears bright is 1037.5 angstrom\n",
+        "The thickness of the film that appears dark is 2075.0 angstrom\n"
+       ]
+      }
+     ],
+     "prompt_number": 7
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 3.5, Page number 72"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "lamda = 5893;    #Wavelength of monochromatic lihgt used(A)\n",
+      "n = 10;    #Number of fringe that are found \n",
+      "d = 1;     #Distance of 10 fringes(cm)\n",
+      "\n",
+      "#Calculation\n",
+      "beta = d/n;    #Fringe width(cm)\n",
+      "lamda = lamda*10**-8;    #Wavelength of monochromatic lihgt used(cm)\n",
+      "theta = lamda/(2*beta);    #Angle of the wedge(rad)\n",
+      "theta = theta*10**4;\n",
+      "theta = math.ceil(theta*10**4)/10**4;     #rounding off the value of theta to 4 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The angle of the wedge is\",theta,\"*10**-4 rad\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The angle of the wedge is 2.9465 *10**-4 rad\n"
+       ]
+      }
+     ],
+     "prompt_number": 12
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 3.6, Page number 72"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "lamda = 5900;    #Wavelength of monochromatic lihgt used(A)\n",
+      "t = 0.010;    #Spacer thickness(mm)\n",
+      "l = 10;    #Wedge length(cm)\n",
+      "\n",
+      "#Calculation\n",
+      "t = t*10**-1;    #Spacer thickness(cm)\n",
+      "theta = t/l;    #Angle of the wedge(rad)\n",
+      "lamda = lamda*10**-8;    #Wavelength of monochromatic lihgt used(cm)\n",
+      "beta = lamda/(2*theta);    #Fringe width(cm)\n",
+      "\n",
+      "#Result\n",
+      "print \"The separation between consecutive bright fringes is\",beta, \"cm\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The separation between consecutive bright fringes is 0.295 cm\n"
+       ]
+      }
+     ],
+     "prompt_number": 13
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 3.7, Page number 72"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "D4 = 0.4;    #Diameter of 4th dark ring(cm)\n",
+      "D12 = 0.7;    #Diameter of 12th dark ring(cm)\n",
+      "\n",
+      "#Calculation\n",
+      "#We have (dn_plus_k**2)-Dn**2 = 4*k*R*lamda\n",
+      "#D12**2-D4**2 = 32*R*lamda and D20**2-D12**2 = 32*R*lamda for k = 8\n",
+      "#since RHS are equal, by equating the LHS we get D12**2-D4**2 = D20**2-D12**2\n",
+      "D20 = math.sqrt((2*D12**2)-D4**2);    #Diameter of 20th dark ring(cm)\n",
+      "D20 = math.ceil(D20*10**4)/10**4;     #rounding off the value of D20 to 4 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The diameter of 20th dark ring is\",D20, \"cm\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The diameter of 20th dark ring is 0.9056 cm\n"
+       ]
+      }
+     ],
+     "prompt_number": 14
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 3.8, Page number 73"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "Dn = 0.30;    #Diameter of nth dark ring with air film(cm)\n",
+      "dn = 0.25;    #Diameter of nth dark ring with liquid film(cm)\n",
+      "\n",
+      "#Calculation\n",
+      "mew = (Dn/dn)**2;    #Refractive index of the liquid\n",
+      "\n",
+      "#Result\n",
+      "print \"The refractive index of the liquid is\", mew\n"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The refractive index of the liquid is 1.44\n"
+       ]
+      }
+     ],
+     "prompt_number": 15
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 3.9, Page number 73"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "x = 0.002945;    #Distance through which movable mirror is shifted(cm)\n",
+      "N = 100;    #Number of fringes shifted\n",
+      "\n",
+      "#Calculation\n",
+      "x = x*10**-2;    #Distance through which movable mirror is shifted(m)\n",
+      "lamda = 2*x/N;   #Wavelength of light(m)\n",
+      "lamda = lamda*10**10;    #Wavelength of light(A)\n",
+      "\n",
+      "#Result\n",
+      "print \"The wavelength of light is\",lamda, \"angstrom\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The wavelength of light is 5890.0 angstrom\n"
+       ]
+      }
+     ],
+     "prompt_number": 16
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 3.10, Page number 73"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "lambda1 = 5896;    #Wavelength of D1 line of sodium(A)\n",
+      "lambda2 = 5890;    #Wavelength of D2 line of sodium(A)\n",
+      "\n",
+      "#Calculation\n",
+      "lamda = (lambda1+lambda2)/2;\n",
+      "x = (lamda**2)/(2*(lambda1-lambda2));    #Shift in movable mirror of Michelson Interferometer(A)\n",
+      "x = x*10**-7;           #Shift in movable mirror of Michelson Interferometer(mm)\n",
+      "x = math.ceil(x*10**4)/10**4;     #rounding off the value of D20 to 4 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The shift in movable mirror is\",x, \"mm\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The shift in movable mirror is 0.2894 mm\n"
+       ]
+      }
+     ],
+     "prompt_number": 17
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": []
+    }
+   ],
+   "metadata": {}
+  }
+ ]
+}
\ No newline at end of file
diff --git a/Engineering_Physics_by_G._Aruldhas/Chapter4_1.ipynb b/Engineering_Physics_by_G._Aruldhas/Chapter4_1.ipynb
new file mode 100755
index 00000000..cc3fca78
--- /dev/null
+++ b/Engineering_Physics_by_G._Aruldhas/Chapter4_1.ipynb
@@ -0,0 +1,490 @@
+{
+ "metadata": {
+  "name": "",
+  "signature": "sha256:3ba769656e990801d788b85df0bb013daae3fbdec7e19bc6ba653a53dfdabcb2"
+ },
+ "nbformat": 3,
+ "nbformat_minor": 0,
+ "worksheets": [
+  {
+   "cells": [
+    {
+     "cell_type": "heading",
+     "level": 1,
+     "metadata": {},
+     "source": [
+      "4: Diffraction"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 4.1, Page number 91"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "from __future__ import division\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "D = 50;    #Distance between source and the screen(cm)\n",
+      "lamda = 6563;    #Wavelength of light of parallel rays(A)\n",
+      "d = 0.385;        #Width of the slit(mm)\n",
+      "n1 = 1;    #Order of diffraction for first minimum\n",
+      "n2 = 5;    #Order of diffraction for fifth minimum\n",
+      "\n",
+      "#Calculation\n",
+      "lamda = lamda*10**-8;        #Wavelength of light of parallel rays(cm)\n",
+      "d = d*10**-1;      #Width of the slit(cm)\n",
+      "#As sin(theta1) = n*lambda/d = x1/D, solving for x1\n",
+      "x1 = n1*lamda*D/d;    #Distance from the centre of the principal maximum to the first minimum(cm)\n",
+      "x1 = x1*10;         #Distance from the centre of the principal maximum to the first minimum(mm)\n",
+      "x1 = math.ceil(x1*10**3)/10**3;     #rounding off the value of x1 to 3 decimals\n",
+      "x2 = n2*lamda*D/d;    #Distance from the centre of the principal maximum to the fifth minimum(cm)\n",
+      "x2 = x2*10;         #Distance from the centre of the principal maximum to the fifth minimum(mm)\n",
+      "x2 = math.ceil(x2*10**3)/10**3;     #rounding off the value of x2 to 3 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The Distance from the centre of the principal maximum to the first minimum is\",x1, \"mm\"\n",
+      "print \"The Distance from the centre of the principal maximum to the fifth minimum is\",x2, \"mm\"\n",
+      "\n",
+      "#answer for x2 given in the book is wrong"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The Distance from the centre of the principal maximum to the first minimum is 0.853 mm\n",
+        "The Distance from the centre of the principal maximum to the fifth minimum is 4.262 mm\n"
+       ]
+      }
+     ],
+     "prompt_number": 1
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 4.2, Page number 91"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "from __future__ import division\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "D = 0.04;    #Diameter of circular aperture(cm)\n",
+      "f = 20;      #Focal length of convex lens(cm)\n",
+      "lamda = 6000;    #Wavelength of light used(A)\n",
+      "\n",
+      "#Calculation\n",
+      "lamda = lamda*10**-8;    #Wavelength of light used(cm)\n",
+      "#We have sin(theta) = 1.22*lambda/D = theta, for small theta\n",
+      "#For first dark ring\n",
+      "theta = 1.22*lamda/D;    #The half angular width at central maximum(rad)\n",
+      "r1 = theta*f;    #The half width of central maximum for first dark ring(cm)\n",
+      "r1 = r1*10**2;\n",
+      "#We have sin(theta) = 5.136*lambda/(%pi*D) = theta, for small theta\n",
+      "#For second dark ring\n",
+      "theta = 5.136*lamda/(math.pi*D);    #The half angular width at central maximum(rad)\n",
+      "r2 = theta*f;    #The half width of central maximum for second dark ring(cm)\n",
+      "r2 = r2*10**2;\n",
+      "r2 = math.ceil(r2*100)/100;     #rounding off the value of r2 to 2 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The radius of first dark ring is\",r1,\"*10**-2 cm\"\n",
+      "print \"The radius of second dark ring is\",r2,\"*10**-2 cm\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The radius of first dark ring is 3.66 *10**-2 cm\n",
+        "The radius of second dark ring is 4.91 *10**-2 cm\n"
+       ]
+      }
+     ],
+     "prompt_number": 6
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 4.3, Page number 92"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "n = 2;    #Order of diffraction\n",
+      "lamda = 650;    #Wavelength of light used(nm)\n",
+      "d = 1.2*10**-3;    #Distance between two consecutive slits of grating(cm)\n",
+      "\n",
+      "#Calculation\n",
+      "#We have sin(theta) = n*N*lambda = n*lambda/d, solving for theta\n",
+      "lamda = lamda*10**-9;     #Wavelength of light used(m)\n",
+      "d = d*10**-2;    #Distance between two consecutive slits of grating(m)\n",
+      "a=n*lamda/d;\n",
+      "theta = math.asin(a);     #Angle at which the 650 nm light produces a second order maximum(rad)\n",
+      "theta = theta*57.2957795;     #angle in degrees\n",
+      "theta = math.ceil(theta*10**2)/10**2;     #rounding off the value of theta to 2 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The angle at which the light produces a second order maximum is\",theta, \"degrees\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The angle at which the light produces a second order maximum is 6.22 degrees\n"
+       ]
+      }
+     ],
+     "prompt_number": 7
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 4.4, Page number 92"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "lamda = 650;    #Wavelength of light used(nm)\n",
+      "N = 6000;    #Number of lines per cm on grating\n",
+      "theta = 90;    #Angle at which the highest spectral order is obtained(degrees)\n",
+      "\n",
+      "#Calculation\n",
+      "theta = theta*0.0174532925;     #Angle at which the highest spectral order is obtained(rad)\n",
+      "#We have sin(theta) = n*N*lambda, solving for n\n",
+      "lamda = lamda*10**-9;    #Wavelength of light used(m)\n",
+      "N = N*10**2;    #Number of lines per m on grating\n",
+      "n = math.sin(theta)/(N*lamda);      #The highest order of spectra with diffraction grating\n",
+      "n = math.ceil(n*10**3)/10**3;     #rounding off the value of theta to 3 decimals\n",
+      "i,d = divmod(n, 1);     #divides the value of n into integer and decimal parts where i is integer\n",
+      "\n",
+      "#Result\n",
+      "print \"value of n is\",n\n",
+      "print \"The highest order of spectra obtained with diffraction grating is\",i\n"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "value of n is 2.565\n",
+        "The highest order of spectra obtained with diffraction grating is 2.0\n"
+       ]
+      }
+     ],
+     "prompt_number": 8
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 4.5, Page number 92"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "N = 4000;    #Number of lines per cm on grating\n",
+      "#For Blue Line\n",
+      "lamda1 = 450;    #Wavelength of blue light(nm)\n",
+      "n1 = 3;    #Order of diffraction spectrum\n",
+      "#For Red Line\n",
+      "lamda2 = 700;    #Wavelength of red light(nm)\n",
+      "n2 = 2;    #Order of diffraction spectrum\n",
+      "\n",
+      "#Calculation\n",
+      "N = N*10**2;    #Number of lines per m on grating\n",
+      "lamda1 = lamda1*10**-9;     #Wavelength of blue light(m)\n",
+      "lamda2 = lamda2*10**-9;     #Wavelength of red light(m)\n",
+      "#We have sin(theta) = n*N*lambda, solving for sin(theta)\n",
+      "sin_theta_3 = n1*N*lamda1;    #Sine of angle at third order diffraction \n",
+      "sin_theta_2 = n2*N*lamda2;    #Sine of angle at second order diffraction\n",
+      "\n",
+      "#Result\n",
+      "print \"Sine of angle at third order diffraction is\",sin_theta_3\n",
+      "print \"Sine of angle at second order diffraction is\",sin_theta_2    \n",
+      "#Check for overlapping\n",
+      "if (sin_theta_2-sin_theta_3)<0.05:\n",
+      "    print \"The two orders overlap\"\n",
+      "else:\n",
+      "     print \"The two orders do not overlap\"   "
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Sine of angle at third order diffraction is 0.54\n",
+        "Sine of angle at second order diffraction is 0.56\n",
+        "The two orders overlap\n"
+       ]
+      }
+     ],
+     "prompt_number": 9
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 4.6, Page number 93"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "n = 1;    #Order of diffraction spectrum\n",
+      "N = 6000;    #Number of lines per cm on diffraction grating\n",
+      "D = 2;    #Distance of screen from the source(m)\n",
+      "lamda1 = 400;    #Wavelength of blue light(nm)\n",
+      "lamda2 = 750;    #Wavelength of blue light(nm)\n",
+      "\n",
+      "#Calculation\n",
+      "N = N*10**2;    #Number of lines per m on grating\n",
+      "lamda1 = lamda1*10**-9;     #Wavelength of blue light(m)\n",
+      "lamda2 = lamda2*10**-9;     #Wavelength of blue light(m)\n",
+      "#We have sin(theta1) = n*N*lamda1, solving for theta1\n",
+      "theta1 = math.asin(n*N*lamda1);    #Angle at first order diffraction for Blue light(rad)\n",
+      "theta1_d = theta1*57.2957795;     #Angle at first order diffraction for Blue light(degrees)\n",
+      "theta2 = math.asin(n*N*lamda2);    #Angle at first order diffraction for Red light(rad)\n",
+      "theta2_d = theta2*57.2957795;      #Angle at first order diffraction for Red light(degrees)\n",
+      "x1 = D*math.tan(theta1);    #Half width position at central maximum for blue color(m)\n",
+      "x2 = D*math.tan(theta2);    #Half width position at central maximum for red color(m)\n",
+      "x = x2-x1;      #width of first order spectrum on the screen(m)\n",
+      "x = x*10**2;    #width of first order spectrum on the screen(cm)\n",
+      "x = math.ceil(x*10**2)/10**2;     #rounding off the value of x to 2 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The width of first order spectrum on the screen is\",x, \"cm\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The width of first order spectrum on the screen is 51.34 cm\n"
+       ]
+      }
+     ],
+     "prompt_number": 10
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 4.7, Page number 93"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "w = 5;    #Width of the grating(cm)\n",
+      "N = 32;    #Number of lines per mm on grating\n",
+      "lamda = 640;    #Wavelength of light(nm)\n",
+      "n = 2;    #Order of diffraction\n",
+      "\n",
+      "#Calculation\n",
+      "N= N*10;    #Number of lines per cm on grating\n",
+      "N0 = w*N;   #Total number of lines on the grating\n",
+      "d_lambda = lamda/(n*N0);    #Separation between wavelengths(nm)\n",
+      "\n",
+      "#Result\n",
+      "print \"The separation between wavelengths which the grating can just resolve is\",d_lambda, \"nm\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The separation between wavelengths which the grating can just resolve is 0.2 nm\n"
+       ]
+      }
+     ],
+     "prompt_number": 11
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 4.8, Page number 93"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "lamda = 550;    #Wavelength of light(nm)\n",
+      "D = 3.2;    #Diameter of circular lens(cm)\n",
+      "f = 24;     #Focal length of the lens(cm)  \n",
+      "\n",
+      "#Calculation\n",
+      "lamda = lamda*10**-9;    #Wavelength of light(m)\n",
+      "D = D*10**-2;    #Diameter of circular lens(m)\n",
+      "theta_min = 1.22*lamda/D;    #Minimum angle of resolution provided by the lens(rad)\n",
+      "#As delta_x/f = theta_min, solving for delta_x\n",
+      "f = f*10**-2;    #Focal length of the lens(m) \n",
+      "delta_x = theta_min*f;     #Separation of the centres of the images in the focal plane of lens(m)\n",
+      "delta_x = delta_x*10**6;    #Separation of the centres of the images in the focal plane of lens(micro m)\n",
+      " \n",
+      "#Result\n",
+      "print \"The separation of the centres of the images in the focal plane is\",round(delta_x), \"micro-metre\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The separation of the centres of the images in the focal plane is 5.0 micro-metre\n"
+       ]
+      }
+     ],
+     "prompt_number": 12
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 4.9, Page number 94"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "lamda = 550;    #Wavelength of light(nm)\n",
+      "D = 20;     #Diameter of objective of telescope(cm)\n",
+      "d = 6;     #Distance of two points from the objective of telescope(km)\n",
+      "\n",
+      "#Calculation\n",
+      "lamda = lamda*10**-9;    #Wavelength of light(m)\n",
+      "D = D*10**-2;    #Diameter of objective of telescope(m)\n",
+      "d = d*10**3;    #Distance of two points from the objective of telescope(m)\n",
+      "theta = 1.22*lamda/D;    #Angular separation between two points(rad)\n",
+      "x = theta*d;    #Linear separation between two points(m)\n",
+      "x = x*10**3;    #Linear separation between two points(mm)\n",
+      "\n",
+      "#Result\n",
+      "print \"The linear separation between two points is\",x, \"mm\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The linear separation between two points is 20.13 mm\n"
+       ]
+      }
+     ],
+     "prompt_number": 13
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": []
+    }
+   ],
+   "metadata": {}
+  }
+ ]
+}
\ No newline at end of file
diff --git a/Engineering_Physics_by_G._Aruldhas/Chapter5_1.ipynb b/Engineering_Physics_by_G._Aruldhas/Chapter5_1.ipynb
new file mode 100755
index 00000000..8b5822ee
--- /dev/null
+++ b/Engineering_Physics_by_G._Aruldhas/Chapter5_1.ipynb
@@ -0,0 +1,299 @@
+{
+ "metadata": {
+  "name": "",
+  "signature": "sha256:d6b4557b658267af4573aff55394c33f7ae58a19c1bc5291838cb933f306de2e"
+ },
+ "nbformat": 3,
+ "nbformat_minor": 0,
+ "worksheets": [
+  {
+   "cells": [
+    {
+     "cell_type": "heading",
+     "level": 1,
+     "metadata": {},
+     "source": [
+      "5: Polarization"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 5.1, Page number 113"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "from __future__ import division\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "mew_g = 1.72;    #Refractive index of glass\n",
+      "mew_w = 4/3;      #Refractive index of water\n",
+      "\n",
+      "#Calculation\n",
+      "#For polarization to occur on flint glass, tan(i) = mew_g/mew_w\n",
+      "#Solving for i\n",
+      "i_g = math.atan(mew_g/mew_w);      #angle of incidence for complete polarization for flint glass(rad)\n",
+      "a = 180/math.pi;       #conversion factor from radians to degrees\n",
+      "i_g = i_g*a;      #angle of incidence(degrees)\n",
+      "i_g = math.ceil(i_g*10**2)/10**2;     #rounding off the value of i_g to 2 decimals\n",
+      "#For polarization to occur on water, tan(i) = mew_w/mew_g\n",
+      "#Solving for i\n",
+      "i_w = math.atan(mew_w/mew_g);     #angle of incidence for complete polarization for water(rad)\n",
+      "i_w = i_w*a;       #angle of incidence(degrees)\n",
+      "i_w = math.ceil(i_w*10**3)/10**3;     #rounding off the value of i_w to 3 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The angle of incidence for complete polarization to occur on flint glass is\",i_g, \"degrees\"\n",
+      "print \"The angle of incidence for complete polarization to occur on water is\",i_w, \"degrees\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The angle of incidence for complete polarization to occur on flint glass is 52.22 degrees\n",
+        "The angle of incidence for complete polarization to occur on water is 37.783 degrees\n"
+       ]
+      }
+     ],
+     "prompt_number": 5
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 5.2, Page number 113"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "from __future__ import division\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "I0 = 1;    #For simplicity, we assume the intensity of light falling on the second Nicol prism to be unity(W/m**2)\n",
+      "theta = 30;    #Angle through which the crossed Nicol is rotated(degrees)\n",
+      "\n",
+      "#Calculation\n",
+      "theeta = 90-theta;     #angle between the planes of transmission after rotating through 30 degrees\n",
+      "a = math.pi/180;           #conversion factor from degrees to radians\n",
+      "theeta = theeta*a;     ##angle between the planes of transmission(rad)\n",
+      "I = I0*math.cos(theeta)**2;    #Intensity of the emerging light from second Nicol(W/m**2)\n",
+      "T = (I/(2*I0))*100;    #Percentage transmission of incident light\n",
+      "T = math.ceil(T*100)/100;     #rounding off the value of T to 2 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The percentage transmission of incident light after emerging through the Nicol prism is\",T, \"%\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The percentage transmission of incident light after emerging through the Nicol prism is 12.51 %\n"
+       ]
+      }
+     ],
+     "prompt_number": 6
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 5.3, Page number 113"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "from __future__ import division\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "lamda = 6000;    #Wavelength of incident light(A)\n",
+      "mew_e = 1.55;    #Refractive index of extraordinary ray\n",
+      "mew_o = 1.54;     #Refractive index of ordinary ray\n",
+      "\n",
+      "#Calculation\n",
+      "lamda = lamda*10**-8;      #Wavelength of incident light(cm)\n",
+      "t = lamda/(4*(mew_e-mew_o));    #Thickness of Quarter Wave plate of positive crystal(cm)\n",
+      "\n",
+      "#Result\n",
+      "print \"The thickness of Quarter Wave plate is\",t, \"cm\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The thickness of Quarter Wave plate is 0.0015 cm\n"
+       ]
+      }
+     ],
+     "prompt_number": 7
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 5.4, Page number 114"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#Calculation\n",
+      "#the thickness of a half wave plate of calcite for wavelength lamda is\n",
+      "#t = lamda/(2*(mew_e - mew_o)) = (2*lamda)/(4*(mew_e - mew_o))\n",
+      "\n",
+      "#Result\n",
+      "print \"The half wave plate for lamda will behave as a quarter wave plate for 2*lamda for negligible variation of refractive index with wavelength\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The half wave plate for lamda will behave as a quarter wave plate for 2*lamda for negligible variation of refractive index with wavelength\n"
+       ]
+      }
+     ],
+     "prompt_number": 8
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 5.5, Page number 114"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#importing modules\n",
+      "from __future__ import division\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "lamda = 500;    #Wavelength of incident light(nm)\n",
+      "mew_e = 1.5508;    #Refractive index of extraordinary ray\n",
+      "mew_o = 1.5418;     #Refractive index of ordinary ray\n",
+      "t = 0.032;     #Thickness of quartz plate(mm)\n",
+      "\n",
+      "#Calculation\n",
+      "lamda = lamda*10**-9;     #Wavelength of incident light(m)\n",
+      "t = t*10**-3;     #Thickness of quartz plate(m)\n",
+      "dx = (mew_e - mew_o)*t;    #Path difference between E-ray and O-ray(m)\n",
+      "dphi = (2*math.pi)/lamda*dx;    #Phase retardation for quartz for given wavelength(rad)\n",
+      "dphi = dphi/math.pi;\n",
+      "\n",
+      "#Result\n",
+      "print \"The phase retardation for quartz for given wavelength is\",dphi, \"pi rad\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The phase retardation for quartz for given wavelength is 1.152 pi rad\n"
+       ]
+      }
+     ],
+     "prompt_number": 9
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 5.6, Page number 114"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "C = 52;    #Critical angle for total internal reflection(degrees)\n",
+      "\n",
+      "#Calculation\n",
+      "a = math.pi/180;           #conversion factor from degrees to radians\n",
+      "C = C*a;      #Critical angle for total internal reflection(rad)\n",
+      "#From Brewster's law, math.tan(i_B) = 1_mew_2\n",
+      "#Also math.sin(C) = 1_mew_2, so that math.tan(i_B) = math.sin(C), solving for i_B\n",
+      "i_B = math.atan(math.sin(C));    #Brewster angle at the boundary(rad)\n",
+      "b = 180/math.pi;           #conversion factor from radians to degrees\n",
+      "i_B = i_B*b;     #Brewster angle at the boundary(degrees)\n",
+      "\n",
+      "#Result\n",
+      "print \"The Brewster angle at the boundary between two materials is\",int(i_B), \"degrees\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The Brewster angle at the boundary between two materials is 38 degrees\n"
+       ]
+      }
+     ],
+     "prompt_number": 13
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": [],
+     "prompt_number": 10
+    }
+   ],
+   "metadata": {}
+  }
+ ]
+}
\ No newline at end of file
diff --git a/Engineering_Physics_by_G._Aruldhas/Chapter6_1.ipynb b/Engineering_Physics_by_G._Aruldhas/Chapter6_1.ipynb
new file mode 100755
index 00000000..0de10069
--- /dev/null
+++ b/Engineering_Physics_by_G._Aruldhas/Chapter6_1.ipynb
@@ -0,0 +1,666 @@
+{
+ "metadata": {
+  "name": "",
+  "signature": "sha256:1812f754f8541ce5ac6b5aaa71f7eac9ff30ca728d742f618ea7c5d3873d8a96"
+ },
+ "nbformat": 3,
+ "nbformat_minor": 0,
+ "worksheets": [
+  {
+   "cells": [
+    {
+     "cell_type": "heading",
+     "level": 1,
+     "metadata": {},
+     "source": [
+      "6: Crystallography"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 6.1, Page number 134"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "M = 23+35.5;        #Molecular weight of NaCl(kg/k-mole)\n",
+      "d = 2.18*10**3;     #Density of rock salt(kg/m**3)\n",
+      "n = 4;    #Number of atoms per unit cell for an fcc lattice of NaCl crystal\n",
+      "N = 6.02*10**26;    #Avogadro's No., atoms/k-mol\n",
+      "\n",
+      "#Calculation\n",
+      "a = (n*M/(d*N))**(1/3);     #Lattice constant of unit cell of NaCl(m)\n",
+      "a = a*10**9;      ##Lattice constant of unit cell of NaCl(nm)\n",
+      "a = math.ceil(a*10**3)/10**3;     #rounding off the value of a to 3 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"Lattice parameter for the NaCl crystal is\",a, \"nm\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Lattice parameter for the NaCl crystal is 0.563 nm\n"
+       ]
+      }
+     ],
+     "prompt_number": 1
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 6.2, Page number 134"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "m = 3;\n",
+      "n = 2; \n",
+      "p = 1;     #Coefficients of intercepts along three axes\n",
+      "\n",
+      "#Calculation\n",
+      "#reciprocals of the intercepts are 1/m, 1/n, 1/p i.e 1/3, 1/2, 1\n",
+      "#multiplying by LCM the reciprocals become 2, 3, 6\n",
+      "\n",
+      "#Result\n",
+      "print \"The required miller indices are : (2, 3, 6)\"\n"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The required miller indices are : (2, 3, 6)\n"
+       ]
+      }
+     ],
+     "prompt_number": 2
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 6.3, Page number 135"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "m = 2;  #Coefficient of intercept along x-axis\n",
+      "#n = infinite    Coefficient of intercept along y-axis\n",
+      "p = 3/2;    #Coefficient of intercept along z-axis\n",
+      "\n",
+      "#Calculation\n",
+      "#reciprocals of the intercepts are 1/m, 1/n, 1/p i.e 1/2, 0, 2/3\n",
+      "#multiplying by LCM the reciprocals become 3, 0, 4\n",
+      "\n",
+      "#Result\n",
+      "print \"The required miller indices are : (3, 0, 4)\"\n"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The required miller indices are : (3, 0, 4)\n"
+       ]
+      }
+     ],
+     "prompt_number": 3
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 6.4, Sketching not possible"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 6.5, Page number 136"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "#For (110) planes\n",
+      "h1 = 1;\n",
+      "k1 = 1;\n",
+      "l1 = 0;    #Miller Indices for planes in a cubic crystal\n",
+      "a1 = 0.43;     #Interatomic spacing(nm)\n",
+      "#For (212) planes\n",
+      "h2 = 2; \n",
+      "k2 = 1;\n",
+      "l2 = 2;    #Miller Indices for planes in a cubic crystal\n",
+      "a2 = 0.43;     #Interatomic spacing(nm)\n",
+      "\n",
+      "#Calculation\n",
+      "d1 = a1/(h1**2+k1**2+l1**2)**(1/2);  #The interplanar spacing for cubic crystals(nm)\n",
+      "d1 = math.ceil(d1*10**4)/10**4;     #rounding off the value of d1 to 4 decimals\n",
+      "d2 = a2/(h2**2+k2**2+l2**2)**(1/2);    #The interplanar spacing for cubic crystals(nm)\n",
+      "d2 = math.ceil(d2*10**4)/10**4;     #rounding off the value of d2 to 4 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The interplanar spacing between consecutive (110) planes is\",d1, \"nm\";\n",
+      "print \"The interplanar spacing between consecutive (212) planes is\",d2, \"nm\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The interplanar spacing between consecutive (110) planes is 0.3041 nm\n",
+        "The interplanar spacing between consecutive (212) planes is 0.1434 nm\n"
+       ]
+      }
+     ],
+     "prompt_number": 4
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 6.6, Page number 136"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "h = 2;\n",
+      "k = 3;\n",
+      "l = 1;      #Miller Indices for planes in a cubic crystal\n",
+      "r = 0.175;    #Atomic radius of fcc lattice(nm)\n",
+      "\n",
+      "#Calculation\n",
+      "a = 2*math.sqrt(2)*r;     #Interatomic spacing of fcc lattice(nm)\n",
+      "d = a/(h**2+k**2+l**2)**(1/2);    #The interplanar spacing for cubic crystals(nm)\n",
+      "d = math.ceil(d*10**4)/10**4;     #rounding off the value of d to 4 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The interplanar spacing between consecutive (231) planes is\",d, \"nm\"\n"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The interplanar spacing between consecutive (231) planes is 0.1323 nm\n"
+       ]
+      }
+     ],
+     "prompt_number": 5
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 6.7, Page number 136"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "lamda = 1.44;      #Wavelength of X-rays(A)\n",
+      "d = 2.8;     #Interplanar spacing of rocksalt crystal(A)\n",
+      "n1 = 1;      #For 1st Order diffraction\n",
+      "n2 = 2;     #For 2nd Order diffraction\n",
+      "\n",
+      "#Calculation\n",
+      "theta1 = math.asin(n1*lamda/(2*d));    #Angle of diffraction(radians)\n",
+      "theeta1 = theta1*57.2957795;       #Angle of diffraction(degrees)\n",
+      "theeta1 = math.ceil(theeta1*10**2)/10**2;     #rounding off the value of theeta1 to 2 decimals\n",
+      "theta2 = math.asin(n2*lamda/(2*d));     #Angle of diffraction(radians)\n",
+      "theeta2 = theta2*57.2957795;       #Angle of diffraction(degrees)\n",
+      "theeta2 = math.ceil(theeta2*10**2)/10**2;     #rounding off the value of theeta2 to 2 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The angle of diffraction for first order maxima is\",theeta1, \"degrees\"\n",
+      "print \"The angle of diffraction for second order maxima is\",theeta2, \"degrees\"\n"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The angle of diffraction for first order maxima is 14.91 degrees\n",
+        "The angle of diffraction for second order maxima is 30.95 degrees\n"
+       ]
+      }
+     ],
+     "prompt_number": 6
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 6.8, Page number 136"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "a = 1;     #For convenience, assume interatomic spacing to be unity(m)\n",
+      "\n",
+      "#Calculation\n",
+      "N = 8*(1/8) + 6*(1/2);      #total number of spheres in a unit cell\n",
+      "r = a/(2*math.sqrt(2));    #The atomic radius(m)\n",
+      "V_atom = N*(4/3)*math.pi*r**3;    #Volume of atoms(m**3)\n",
+      "V_uc = a**3;       #Volume of unit cell(m**3)\n",
+      "PV = (V_atom/V_uc)*100;      #percentage of actual volume\n",
+      "PV = math.ceil(PV*10)/10;     #rounding off the value of PV to 1 decimal\n",
+      "\n",
+      "#Result\n",
+      "print \"The percentage of actual volume occupied by the spheres in fcc structure is\",PV, \"percent\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The percentage of actual volume occupied by the spheres in fcc structure is 74.1 percent\n"
+       ]
+      }
+     ],
+     "prompt_number": 7
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 6.9, Page number 137"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "#For (221) planes\n",
+      "h = 2; \n",
+      "k = 2; \n",
+      "l = 1;    #Miller Indices for planes in a cubic crystal\n",
+      "a = 2.68;    #Interatomic spacing(A)\n",
+      "n1 = 1;      #First Order of diffraction \n",
+      "n2 = 2;    #Second order of diffraction\n",
+      "theta1 = 8.5;    #Glancing angle at which Bragg's reflection occurs(degrees)\n",
+      "\n",
+      "#Calculation\n",
+      "theta1 = theta1*0.0174532925;     #Glancing angle at which Bragg's reflection occurs(radians)\n",
+      "a = a*10**-10;      #Interatomic spacing(m)\n",
+      "d = a/(h**2+k**2+l**2)**(1/2);   #The interplanar spacing for cubic crystal(m)\n",
+      "lamda = 2*d*math.sin(theta1)/n1;     #Bragg's Law for wavelength of X-rays(m)\n",
+      "lamda_A = lamda*10**10;        #Bragg's Law for wavelength of X-rays(A)\n",
+      "lamda_A = math.ceil(lamda_A*10**4)/10**4;     #rounding off the value of lamda_A to 4 decimals\n",
+      "theta2 = math.asin(n2*lamda/(2*d));    #Angle at which second order Bragg reflection occurs(radians)\n",
+      "theta2 = theta2*57.2957795;       #Angle at which second order Bragg reflection occurs(degrees)\n",
+      "theta2 = math.ceil(theta2*10)/10;     #rounding off the value of theta2 to 1 decimal\n",
+      "\n",
+      "#Result\n",
+      "print \"The interplanar spacing between consecutive (221) planes is\",d, \"m\"\n",
+      "print \"The wavelength of X-rays is\",lamda_A, \"angstrom\"\n",
+      "print \"The angle at which second order Bragg reflection occurs is\",theta2, \"degrees\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The interplanar spacing between consecutive (221) planes is 8.93333333333e-11 m\n",
+        "The wavelength of X-rays is 0.2641 angstrom\n",
+        "The angle at which second order Bragg reflection occurs is 17.2 degrees\n"
+       ]
+      }
+     ],
+     "prompt_number": 9
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 6.10, Page number 137"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "h = 1; \n",
+      "k = 1;\n",
+      "l = 0;    #Miller Indices for planes in a cubic crystal\n",
+      "n = 1;    #First Order of diffraction \n",
+      "theta = 25;    #Glancing angle at which Bragg's reflection occurs(degrees)\n",
+      "lamda = 0.7;     #Wavelength of X-rays(A)\n",
+      "\n",
+      "#Calculation\n",
+      "theta = theta*0.0174532925;     #Glancing angle at which Bragg's reflection occurs(radians)\n",
+      "d = n*lamda/(2*math.sin(theta));    #Interplanar spacing of cubic crystal(A)\n",
+      "a = d*(h**2+k**2+l**2)**(1/2);      #The lattice parameter for cubic crystal(A)\n",
+      "a = math.ceil(a*10**3)/10**3;     #rounding off the value of a to 3 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The lattice parameter for cubic crystal is\",a, \"angstrom\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The lattice parameter for cubic crystal is 1.172 angstrom\n"
+       ]
+      }
+     ],
+     "prompt_number": 10
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 6.11, Page number 138"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "d = 0.31;      #Interplanar spacing(nm)\n",
+      "n = 1;    #First Order of diffraction \n",
+      "theta = 9.25;    #Glancing angle at which Bragg's reflection occurs(degrees)\n",
+      "theta_max = 90;     #Maximum possible angle at which reflection can occur(degrees)\n",
+      "theta_max = theta_max*0.0174532925;      #Maximum possible angle at which reflection can occur(radians)\n",
+      "\n",
+      "#Calculation\n",
+      "theta = theta*0.0174532925;    #Glancing angle at which Bragg's reflection occurs(radians)\n",
+      "lamda = 2*d*math.sin(theta)/n;    #Wavelength of X-rays(nm) (Bragg's Law)\n",
+      "lamda = math.ceil(lamda*10**5)/10**5;     #rounding off the value of lamda to 5 decimals\n",
+      "n = 2*d*math.sin(theta_max)/lamda;    #Maximum possible order of diffraction\n",
+      "\n",
+      "#Result\n",
+      "print \"The wavelength of X-rays is\",lamda, \"nm\"\n",
+      "print \"The Maximum possible order of diffraction is\",round(n)"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The wavelength of X-rays is 0.09967 nm\n",
+        "The Maximum possible order of diffraction is 6.0\n"
+       ]
+      }
+     ],
+     "prompt_number": 11
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 6.12, Page number 138"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "#For (110) planes\n",
+      "h1 = 1;\n",
+      "k1 = 1;\n",
+      "l1 = 0;     #Miller indices for (110) planes\n",
+      "d_110 = 0.195;     #Interplanar spacing between (110) planes(nm)\n",
+      "#For (210) planes\n",
+      "h2 = 2;\n",
+      "k2 = 1; \n",
+      "l2 = 0;     #Miller indices for (110) planes\n",
+      "n = 2;     #Second Order of diffraction \n",
+      "lamda = 0.071;     #Wavelength of X-rays(nm)\n",
+      "\n",
+      "#Calculation\n",
+      "a = d_110*(h1**2 + k1**2 + l1**2)**(1/2);     #Lattice parameter for bcc crystal(nm)\n",
+      "d_210 = a/(h2**2 + k2**2 + l2**2)**(1/2);     #Interplanar spacing between (210) planes(nm)\n",
+      "theta = math.asin(n*lamda/(2*d_210));      #Bragg reflection angle for the second order diffraction(radians)\n",
+      "theeta = theta*57.2957795;      #Bragg reflection angle for the second order diffraction(degrees)\n",
+      "theeta = math.ceil(theeta*10**3)/10**3;     #rounding off the value of theeta to 3 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"Bragg reflection angle for the second order diffraction is\",theeta, \"degrees\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Bragg reflection angle for the second order diffraction is 35.149 degrees\n"
+       ]
+      }
+     ],
+     "prompt_number": 12
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 6.13, Page number 138"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "d = 2182;       #Density of rock salt(kg/m**3)\n",
+      "n = 4;        #Number of atoms per unit cell for an fcc lattice of NaCl crystal\n",
+      "N = 6.02*10**26;    #Avogadro's number(atoms/k-mol)\n",
+      "\n",
+      "#Calculation\n",
+      "M = 23+35.5;         #Molecular weight of NaCl(kg/k-mole)\n",
+      "#V = a^3 = M*n/(N*d)\n",
+      "a = (n*M/(d*N))**(1/3);      #Lattice constant of unit cell of NaCl(m)\n",
+      "D = a/2;       #distance between nearest neighbours(m)\n",
+      "D = D*10**9;    #distance between nearest neighbours(nm)\n",
+      "D = math.ceil(D*10**4)/10**4;     #rounding off the value of D to 4 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The distance between nearest neighbours of NaCl structure is\",D, \"nm\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The distance between nearest neighbours of NaCl structure is 0.2814 nm\n"
+       ]
+      }
+     ],
+     "prompt_number": 13
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 6.14, Page number 139"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "r1 = 1.258;     #Atomic radius of bcc structure of iron(A)\n",
+      "N1 = 2;     #Number of atoms per unit cell in bcc structure\n",
+      "#For fcc structure\n",
+      "r2 = 1.292;     #Atomic radius of fcc structure of iron(A)\n",
+      "N2 = 4;     #Number of atoms per unit cell in fcc structure\n",
+      "\n",
+      "#Calculation\n",
+      "a1 = 4*r1/math.sqrt(3);    #Lattice parameter of bcc structure of iron(A)\n",
+      "V1 = a1**3;     #Volume of bcc unit cell(A)\n",
+      "V_atom_bcc = V1/N1;    #Volume occupied by one atom(A)\n",
+      "a2 = 2*math.sqrt(2)*r2;     #Lattice parameter of fcc structure of iron(A)\n",
+      "V2 = a2**3;     #Volume of fcc unit cell(A)\n",
+      "V_atom_fcc = V2/N2;     #Volume occupied by one atom(A)\n",
+      "delta_V = (V_atom_bcc-V_atom_fcc)/V_atom_bcc*100;    #Percentage change in volume due to structural change of iron\n",
+      "delta_V = math.ceil(delta_V*10**3)/10**3;     #rounding off the value of delta_V to 3 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The percentage change in volume of iron is\",delta_V, \"percent\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The percentage change in volume of iron is 0.494 percent\n"
+       ]
+      }
+     ],
+     "prompt_number": 15
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": []
+    }
+   ],
+   "metadata": {}
+  }
+ ]
+}
\ No newline at end of file
diff --git a/Engineering_Physics_by_G._Aruldhas/Chapter7_1.ipynb b/Engineering_Physics_by_G._Aruldhas/Chapter7_1.ipynb
new file mode 100755
index 00000000..750a9700
--- /dev/null
+++ b/Engineering_Physics_by_G._Aruldhas/Chapter7_1.ipynb
@@ -0,0 +1,295 @@
+{
+ "metadata": {
+  "name": "",
+  "signature": "sha256:7388a73b9b3de996a0d87179cb12d51f5ad7f3cb764b14aa844019e8d2cdb4ea"
+ },
+ "nbformat": 3,
+ "nbformat_minor": 0,
+ "worksheets": [
+  {
+   "cells": [
+    {
+     "cell_type": "heading",
+     "level": 1,
+     "metadata": {},
+     "source": [
+      "7: Superconductivity"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 7.1, Page number 152"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "from __future__ import division\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "Tc=3.722;      #critical temperature(K)\n",
+      "T=2;          #temperature(K)\n",
+      "Bc_0=0.0305;     #critical field(T)\n",
+      "\n",
+      "#Calculation\n",
+      "Bc_T=Bc_0*(1-(T/Tc)**2);     #critical field at 2K(T)\n",
+      "Bc_T = math.ceil(Bc_T*10**4)/10**4;     #rounding off the value of Bc_T to 4 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The critical field at 2K is\",Bc_T, \"T\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The critical field at 2K is 0.0217 T\n"
+       ]
+      }
+     ],
+     "prompt_number": 1
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 7.2, Page number 152"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#importing modules\n",
+      "from __future__ import division\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "V = 1;     #DC voltage applied across the Josephson junction(micro-volt)\n",
+      "e = 1.6*10**-19;    #Charge on an electron(C)\n",
+      "h = 6.626*10**-34;    #Planck's constant(Js)\n",
+      "\n",
+      "#Calculation\n",
+      "V = V*10**-6;     #DC voltage applied across the Josephson junction(V)\n",
+      "f = 2*e*V/h;      #Frequency of Josephson current(Hz)\n",
+      "f = f*10**-6;      #Frequency of Josephson current(MHz)\n",
+      "f = math.ceil(f*10**2)/10**2;     #rounding off the value of f to 2 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The frequency of Josephson current is\",f, \"MHz\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The frequency of Josephson current is 482.95 MHz\n"
+       ]
+      }
+     ],
+     "prompt_number": 2
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 7.3, Page number 152"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "`\n",
+      "\n",
+      "#importing modules\n",
+      "from __future__ import division\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "T_c = 0.517;    #Critical temperature for cadmium(K)\n",
+      "k = 1.38*10**-23;    #Boltzmann constant(J/K)\n",
+      "e = 1.6*10**-19;     #Energy equivalent of 1 eV(J/eV)\n",
+      "\n",
+      "#Calculation\n",
+      "E_g = 3.5*k*T_c/e;    #Superconducting energy gap at absolute zero(eV)\n",
+      "E_g = E_g*10**4;\n",
+      "E_g = math.ceil(E_g*10**3)/10**3;     #rounding off the value of E_g to 3 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The superconducting energy gap for Cd at absolute zero is\",E_g,\"*10**-4 eV\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The superconducting energy gap for Cd at absolute zero is 1.561 *10**-4 eV\n"
+       ]
+      }
+     ],
+     "prompt_number": 8
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 7.4, Page number 152"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "from __future__ import division\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "e = 1.6*10**-19;    #Energy equivalent of 1 eV(J/eV)\n",
+      "c = 3*10**8;     #Speed of light in free space(m/s)\n",
+      "h = 6.626*10**-34;    #Planck's constant(Js)\n",
+      "E_g = 1.5*10**-4;     #Superconducting energy gap for a material(eV)\n",
+      "\n",
+      "#Calculation\n",
+      "#As E_g = h*new = h*c/lamda, solving for lambda\n",
+      "lamda = h*c/(E_g*e);    #Wavelength of photon to break up a Cooper-pair(m)\n",
+      "lamda = lamda*10**3;\n",
+      "lamda = math.ceil(lamda*10**3)/10**3;     #rounding off the value of lamda to 3 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The wavelength of photon to break up a Cooper-pair is\",lamda,\"*10**-3 m\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The wavelength of photon to break up a Cooper-pair is 8.283 *10**-3 m\n"
+       ]
+      }
+     ],
+     "prompt_number": 12
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 7.5, Page number 153"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "from __future__ import division\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "lambda_0 = 37;     #Penetration depth of lead at 0 kelvin(nm)\n",
+      "T_c = 7.193;      #Critical temperature of superconducting transition for lead(kelvin)\n",
+      "T = 5.2;        #Temperature at which penetration depth for lead becomes lambda_T(kelvin) \n",
+      "\n",
+      "#Calculation\n",
+      "lambda_T = lambda_0*(1-(T/T_c)**4)**(-1/2);     #Penetration depth of lead at 5.2 kelvin(nm)\n",
+      "lambda_T = math.ceil(lambda_T*10)/10;     #rounding off the value of lamda_T to 1 decimal\n",
+      "\n",
+      "#Result\n",
+      "print \"The penetration depth of lead is\",lambda_T, \"nm\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The penetration depth of lead is 43.4 nm\n"
+       ]
+      }
+     ],
+     "prompt_number": 13
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 7.6, Page number 153"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "from __future__ import division\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "M1 = 199;    #Mass of an isotope of mercury(amu)\n",
+      "T_C1 = 4.185;    #Transition temperature of the isoptope of Hg(K)\n",
+      "T_C2 = 4.153;    #Transition temperature of another isoptope of Hg(K)\n",
+      "alpha = 0.5;     #Isotope coefficient\n",
+      "\n",
+      "#Calculation\n",
+      "M2 = M1*(T_C1/T_C2)**(1/alpha);    #Mass of another isotope of mercury(amu)\n",
+      "M2 = math.ceil(M2*100)/100;     #rounding off the value of M2 to 2 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The mass of another isotope of mercury is\",M2, \"amu\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The mass of another isotope of mercury is 202.08 amu\n"
+       ]
+      }
+     ],
+     "prompt_number": 16
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": []
+    }
+   ],
+   "metadata": {}
+  }
+ ]
+}
\ No newline at end of file
diff --git a/Engineering_Physics_by_G._Aruldhas/Chapter8_1.ipynb b/Engineering_Physics_by_G._Aruldhas/Chapter8_1.ipynb
new file mode 100755
index 00000000..af1e48b4
--- /dev/null
+++ b/Engineering_Physics_by_G._Aruldhas/Chapter8_1.ipynb
@@ -0,0 +1,664 @@
+{
+ "metadata": {
+  "name": "",
+  "signature": "sha256:1888e774039c89bc21625752ef2171fa6b8e8f5f67497ebbdba82729676e8946"
+ },
+ "nbformat": 3,
+ "nbformat_minor": 0,
+ "worksheets": [
+  {
+   "cells": [
+    {
+     "cell_type": "heading",
+     "level": 1,
+     "metadata": {},
+     "source": [
+      "8: Special Theory of Relativity"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 8.1, Page number 171"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "L_0 = 1;     #For simplicity, we assume classical length to be unity(m)\n",
+      "c = 1;       #For simplicity assume speed of light to be unity(m/s)\n",
+      "\n",
+      "#Calculation\n",
+      "L = (1-1/100)*L_0;     #Relativistic length(m)\n",
+      "#Relativistic length contraction gives L = L_0*sqrt(1-v^2/c^2), solving for v\n",
+      "v = math.sqrt(1-(L/L_0)**2)*c;    #Speed at which relativistic length is 1 percent of the classical length(m/s)\n",
+      "v = math.ceil(v*10**4)/10**4;     #rounding off the value of v to 4 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The speed at which relativistic length is 1 percent of the classical length is\",v, \"c\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The speed at which relativistic length is 1 percent of the classical length is 0.1411 c\n"
+       ]
+      }
+     ],
+     "prompt_number": 1
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 8.2, Page number 171"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "c = 1;      #For simplicity assume speed of light to be unity(m/s)\n",
+      "delta_t = 5*10**-6;    #Mean lifetime of particles as observed in the lab frame(s)\n",
+      "\n",
+      "#Calculation\n",
+      "v = 0.9*c;    #Speed at which beam of particles travel(m/s)\n",
+      "delta_tau = delta_t*math.sqrt(1-(v/c)**2);     #Proper lifetime of particle as per Time Dilation rule(s)\n",
+      "\n",
+      "#Result\n",
+      "print \"The proper lifetime of particle is\",delta_tau, \"s\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The proper lifetime of particle is 2.17944947177e-06 s\n"
+       ]
+      }
+     ],
+     "prompt_number": 2
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 8.3, Page number 171. theoritical proof"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 8.4, Page number 172"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "c = 1;      #For simplicity assume speed of light to be unity(m/s)\n",
+      "\n",
+      "#Calculation\n",
+      "v = 0.6*c;    #Speed with which the rocket leaves the earth(m/s)\n",
+      "u_prime = 0.9*c;     #Relative speed of second rocket w.r.t. the first rocket(m/s)\n",
+      "u1 = (u_prime+v)/(1+(u_prime*v)/c**2);     #Speed of second rocket for same direction of firing as per Velocity Addition Rule(m/s)\n",
+      "u1 = math.ceil(u1*10**4)/10**4;     #rounding off the value of u1 to 4 decimals\n",
+      "u2 = (-u_prime+v)/(1-(u_prime*v)/c**2);     #Speed of second rocket for opposite direction of firing as per Velocity Addition Rule(m/s)\n",
+      "u2 = math.ceil(u2*10**4)/10**4;     #rounding off the value of u2 to 4 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The speed of second rocket for same direction of firing is\",u1,\"c\"\n",
+      "print \"The speed of second rocket for opposite direction of firing is\",u2,\"c\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The speed of second rocket for same direction of firing is 0.9741 c\n",
+        "The speed of second rocket for opposite direction of firing is -0.6521 c\n"
+       ]
+      }
+     ],
+     "prompt_number": 4
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 8.5, Page number 172"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "c = 1;     #For simplicity assume speed of light to be unity(m/s)\n",
+      "L0 = 1;    #For simplicity assume length in spaceship's frame to be unity(m)\n",
+      "tau = 1;     #Unit time in the spaceship's frame(s)\n",
+      "\n",
+      "#Calculation\n",
+      "L = 1/2*L0;    #Length as observed on earth(m)\n",
+      "#Relativistic length contraction gives L = L_0*sqrt(1-v^2/c^2), solving for v\n",
+      "v = math.sqrt(1-(L/L0)**2)*c;    #Speed at which length of spaceship is observed as half from the earth frame(m/s)\n",
+      "t = tau/math.sqrt(1-(v/c)**2);    #Time dilation of the spaceship's unit time(s)\n",
+      "v = math.ceil(v*10**4)/10**4;     #rounding off the value of v to 4 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The speed at which length of spaceship is observed as half from the earth frame is\",v, \"c\"\n",
+      "print \"The time dilation of the spaceship unit time is\",t,\"delta_tau\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The speed at which length of spaceship is observed as half from the earth frame is 0.8661 c\n",
+        "The time dilation of the spaceship unit time is 2.0 delta_tau\n"
+       ]
+      }
+     ],
+     "prompt_number": 5
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 8.6, Page number 172"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "c = 3*10**8;     #Speed of light in vacuum(m/s)\n",
+      "t1 = 2*10**-7;      #Time for which first event occurs(s)\n",
+      "t2 = 3*10**-7;      #Time for which second event occurs(s)\n",
+      "x1 = 10;       #Position at which first event occurs(m)\n",
+      "x2 = 40;       #Position at which second event occurs(m)\n",
+      "\n",
+      "#Calculation\n",
+      "v = 0.6*c;       #Velocity with which S2 frame moves relative to S1 frame(m/s)\n",
+      "L_factor = 1/math.sqrt(1-(v/c)**2);     #Lorentz factor\n",
+      "delta_t = L_factor*(t2 - t1)+L_factor*v/c**2*(x1 - x2);     #Time difference between the events(s)\n",
+      "delta_x = L_factor*(x2 - x1)-L_factor*v*(t2 - t1);       #Distance between the events(m)\n",
+      "\n",
+      "#Result\n",
+      "print \"The time difference between the events is\",delta_t, \"s\" \n",
+      "print \"The distance between the events is\",delta_x, \"m\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The time difference between the events is 5e-08 s\n",
+        "The distance between the events is 15.0 m\n"
+       ]
+      }
+     ],
+     "prompt_number": 6
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 8.7, Page number 173"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "c = 3*10**8;     #Speed of light in vacuum(m/s)\n",
+      "tau = 2.6*10**-8;     #Mean lifetime the particle in its own frame(s)\n",
+      "d = 20;     #Distance which the unstable particle travels before decaying(m)\n",
+      "\n",
+      "#Calculation\n",
+      "#As t = d/v and also t = tau/sqrt(1-(v/c)^2), so that\n",
+      "#d/v = tau/sqrt(1-(v/c)^2), solving for v\n",
+      "v = math.sqrt(d**2/(tau**2+(d/c)**2));     #Speed of the unstable particle in lab frame(m/s)\n",
+      "v = v/10**8;\n",
+      "v = math.ceil(v*10)/10;     #rounding off the value of v to 1 decimal\n",
+      "\n",
+      "#Result\n",
+      "print \"The speed of the unstable particle in lab frame is\",v,\"*10**8 m/s\"\n"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The speed of the unstable particle in lab frame is 2.8 *10**8 m/s\n"
+       ]
+      }
+     ],
+     "prompt_number": 9
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 8.8, Page number 174"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "c = 1;     #For simplicity assume speed of light to be unity(m/s)\n",
+      "me = 1;    #For simplicity assume mass of electron to be unity(kg)\n",
+      "tau = 2.3*10**-6;     #Average lifetime of mu-meson in rest frame(s)\n",
+      "t = 6.9*10**-6;       #Average lifetime of mu-meson in laboratory frame(s)\n",
+      "e = 1.6*10**-19;     #Energy equivalent of 1 eV(J/eV)\n",
+      "C = 3*10**8;     #Speed of light in vacuum(m/s)\n",
+      "m_e = 9.1*10**-31;     #Mass of an electron(kg)\n",
+      "\n",
+      "#Calculation\n",
+      "#Fromm Time Dilation Rule, tau = t*sqrt(1-(v/c)^2), solving for v\n",
+      "v = c*math.sqrt(1-(tau/t)**2);     #Speed of mu-meson in the laboratory frame(m/s)\n",
+      "v = math.ceil(v*10**5)/10**5;     #rounding off the value of v to 5 decimals\n",
+      "m0 = 207*me;     #Rest mass of mu-meson(kg)\n",
+      "m = m0/math.sqrt(1-(v/c)**2);      #Relativistic variation of mass with velocity(kg)\n",
+      "m = math.ceil(m*10)/10;     #rounding off the value of m to 1 decimal\n",
+      "T = (m*m_e*C**2 - m0*m_e*C**2)/e;     #Kinetic energy of mu-meson(eV)\n",
+      "T = T*10**-6;        #Kinetic energy of mu-meson(MeV)\n",
+      "T = math.ceil(T*100)/100;     #rounding off the value of T to 2 decimals\n",
+      " \n",
+      "#Result\n",
+      "print \"The speed of mu-meson in the laboratory frame is\",v, \"c\"\n",
+      "print \"The effective mass of mu-meson is\",m, \"me\"\n",
+      "print \"The kinetic energy of mu-meson is\",T, \"MeV\"\n"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The speed of mu-meson in the laboratory frame is 0.94281 c\n",
+        "The effective mass of mu-meson is 621.1 me\n",
+        "The kinetic energy of mu-meson is 211.97 MeV\n"
+       ]
+      }
+     ],
+     "prompt_number": 13
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 8.9, Page number 174"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "c = 1;      #For simplicity assume speed of light to be unity(m/s)\n",
+      "m0 = 1;     #For simplicity assume rest mass to be unity(kg)\n",
+      "\n",
+      "#Calculation\n",
+      "m = (20/100+1)*m0;     #Mass in motion(kg)\n",
+      "#As m = m0/sqrt(1-(u/c)^2), solving for u\n",
+      "u = math.sqrt(1-(m0/m)**2)*c;     #Speed of moving mass(m/s) \n",
+      "u = math.ceil(u*10**3)/10**3;     #rounding off the value of u to 3 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The speed of moving body is\",u, \"c\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The speed of moving body is 0.553 c\n"
+       ]
+      }
+     ],
+     "prompt_number": 14
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 8.10, Page number 175"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "c = 3*10**8;     #Speed of light in vacuum(m/s)\n",
+      "dE = 4*10**26;     #Energy radiated per second my the sun(J/s)\n",
+      "\n",
+      "#Calculation\n",
+      "dm = dE/c**2;       #Rate of decrease of mass of sun(kg/s)\n",
+      "dm = dm/10**9;\n",
+      "dm = math.ceil(dm*10**3)/10**3;     #rounding off the value of dm to 3 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The rate of decrease of mass of sun is\",dm,\"*10**9 kg/s\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The rate of decrease of mass of sun is 4.445 *10**9 kg/s\n"
+       ]
+      }
+     ],
+     "prompt_number": 18
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 8.11, Page number 175"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "c = 1;     #For simplicity assume speed of light to be unity(m/s)\n",
+      "m0 = 9.1*10**-31;    #Mass of the electron(kg)\n",
+      "E0 = 0.512;         #Rest energy of electron(MeV)\n",
+      "T = 10;         #Kinetic energy of electron(MeV)\n",
+      "\n",
+      "#Calculation\n",
+      "E = T + E0;     #Total energy of electron(MeV)\n",
+      "# From Relativistic mass-energy relation E^2 = c^2*p^2 + m0^2*c^4, solving for p\n",
+      "p = math.sqrt(E**2-m0**2*c**4)/c;      #Momentum of the electron(MeV)\n",
+      "p = math.ceil(p*100)/100;     #rounding off the value of p to 2 decimals\n",
+      "#As E = E0/sqrt(1-(u/c)^2), solving for u\n",
+      "u = math.sqrt(1-(E0/E)**2)*c;     #Velocity of the electron(m/s)\n",
+      "u = math.ceil(u*10**4)/10**4;     #rounding off the value of u to 4 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The momentum of the electron is\",p,\"/c MeV\"\n",
+      "print \"The velocity of the electron is\",u, \"c\"\n",
+      "\n",
+      "#answer for velocity given in the book is wrong"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The momentum of the electron is 10.52 /c MeV\n",
+        "The velocity of the electron is 0.9989 c\n"
+       ]
+      }
+     ],
+     "prompt_number": 19
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 8.12, Page number 175. theoritical proof"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 8.13, Page number 176"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "c = 3*10**8;      #Speed of light in vacuum(m/s)\n",
+      "E = 4.5*10**17;   #Total energy of object(J)\n",
+      "px = 3.8*10**8;    #X-component of momentum(kg-m/s)\n",
+      "py = 3*10**8;      #Y-component of momentum(kg-m/s)\n",
+      "pz = 3*10**8;      #Z-component of momentum(kg-m/s)\n",
+      "\n",
+      "#Calculation\n",
+      "p = math.sqrt(px**2+py**2+pz**2);     #Total momentum of the object(kg-m/s)\n",
+      "#From Relativistic mass-energy relation E^2 = c^2*p^2 + m0^2*c^4, solving for m0\n",
+      "m0 = math.sqrt(E**2/c**4 - p**2/c**2);    #Rest mass of the body(kg)\n",
+      "m0 = math.ceil(m0*100)/100;     #rounding off the value of m0 to 2 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The rest mass of the body is\",m0, \"kg\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The rest mass of the body is 4.63 kg\n"
+       ]
+      }
+     ],
+     "prompt_number": 20
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 8.14, Page number 176"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "c = 3*10**8;     #Speed of light in vacuum(m/s)\n",
+      "m = 50000;       #Mass of high speed probe(kg)\n",
+      "\n",
+      "#Calculation\n",
+      "u = 0.8*c;       #Speed of the probe(m/s)\n",
+      "p = m*u/math.sqrt(1-(u/c)**2);     #Momentum of the probe(kg-m/s)\n",
+      "\n",
+      "#Result\n",
+      "print \"The momentum of the high speed probe is\",p, \"kg-m/s\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The momentum of the high speed probe is 2e+13 kg-m/s\n"
+       ]
+      }
+     ],
+     "prompt_number": 21
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 8.15, Page number 177"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "e = 1.6*10**-19;     #Electronic charge, C = Energy equivalent of 1 eV(J/eV)\n",
+      "m0 = 9.11*10**-31;   #Rest mass of electron(kg)\n",
+      "c = 3*10**8;     #Speed of light in vacuum(m/s)\n",
+      "\n",
+      "#Calculation\n",
+      "u1 = 0.98*c;     #Inital speed of electron(m/s)\n",
+      "u2 = 0.99*c;     #Final speed of electron(m/s)\n",
+      "m1 = m0/math.sqrt(1-(u1/c)**2);    #Initial relativistic mass of electron(kg)\n",
+      "m2 = m0/math.sqrt(1-(u2/c)**2);    #Final relativistic mass of electron(kg)\n",
+      "dm = m2 - m1;     #Change in relativistic mass of the electron(kg)\n",
+      "W = dm*c**2/e;      #Work done on the electron to change its velocity(eV)\n",
+      "W = W*10**-6;      #Work done on the electron to change its velocity(MeV)\n",
+      "W = math.ceil(W*100)/100;     #rounding off the value of W to 2 decimals\n",
+      "#As W = eV, V = accelerating potential, solving for V\n",
+      "V = W*10**6;     #Accelerating potential(volt)\n",
+      "V = V/10**6;\n",
+      "\n",
+      "#Result\n",
+      "print \"The change in relativistic mass of the electron is\",dm, \"kg\"\n",
+      "print \"The work done on the electron to change its velocity is\",W, \"MeV\"\n",
+      "print \"The accelerating potential is\",V, \"*10**6 volt\"\n",
+      "\n",
+      "#answers given in the book are wrong"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The change in relativistic mass of the electron is 1.87996052912e-30 kg\n",
+        "The work done on the electron to change its velocity is 1.06 MeV\n",
+        "The accelerating potential is 1.06 *10**6 volt\n"
+       ]
+      }
+     ],
+     "prompt_number": 24
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": []
+    }
+   ],
+   "metadata": {}
+  }
+ ]
+}
\ No newline at end of file
diff --git a/Engineering_Physics_by_G._Aruldhas/Chapter9_1.ipynb b/Engineering_Physics_by_G._Aruldhas/Chapter9_1.ipynb
new file mode 100755
index 00000000..af5adbcc
--- /dev/null
+++ b/Engineering_Physics_by_G._Aruldhas/Chapter9_1.ipynb
@@ -0,0 +1,363 @@
+{
+ "metadata": {
+  "name": "",
+  "signature": "sha256:d58e11c98e937b7ff914fc9567035f99fc6ab344053f332f140829887d0ef6cc"
+ },
+ "nbformat": 3,
+ "nbformat_minor": 0,
+ "worksheets": [
+  {
+   "cells": [
+    {
+     "cell_type": "heading",
+     "level": 1,
+     "metadata": {},
+     "source": [
+      "9: Quantum Mechanics"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 9.1, Page number 202"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "V = 100;     #Accelerating potential for electron(volt)\n",
+      "\n",
+      "#Calculation\n",
+      "lamda = math.sqrt(150/V)*10**-10;     #de-Broglie wavelength of electron(m)\n",
+      "\n",
+      "#Result\n",
+      "print \"The De-Broglie wavelength of electron is\",lamda, \"m\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The De-Broglie wavelength of electron is 1.22474487139e-10 m\n"
+       ]
+      }
+     ],
+     "prompt_number": 1
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 9.2, Page number 203"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "e = 1.6*10**-19;     #Energy equivalent of 1 eV(J/eV)\n",
+      "h = 6.626*10**-34;    #Planck's constant(Js)\n",
+      "m = 9.11*10**-31;     #Mass of the electron(kg)\n",
+      "Ek = 10;     #Kinetic energy of electron(eV)\n",
+      "\n",
+      "#Calculation\n",
+      "p = math.sqrt(2*m*Ek*e);     #Momentum of the electron(kg-m/s)\n",
+      "lamda = h/p ;     #de-Broglie wavelength of electron from De-Broglie relation(m)\n",
+      "lamda = lamda*10**9;     #de-Broglie wavelength of electron from De-Broglie relation(nm)\n",
+      "lamda = math.ceil(lamda*10**2)/10**2;     #rounding off the value of lamda to 2 decimals\n",
+      "\n",
+      "#Result\n",
+      "print \"The de-Broglie wavelength of electron is\",lamda, \"nm\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The de-Broglie wavelength of electron is 0.39 nm\n"
+       ]
+      }
+     ],
+     "prompt_number": 2
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 9.3, Page number 203. theoritical proof"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 9.4, Page number 203"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "h = 6.626*10**-34;      #Planck's constant(Js)\n",
+      "m = 9.11*10**-31;       #Mass of the electron(kg)\n",
+      "v = 1.1*10**6;     #Speed of the electron(m/s)\n",
+      "pr = 0.1;        #precision in percent\n",
+      "\n",
+      "#Calculation\n",
+      "p = m*v;     #Momentum of the electron(kg-m/s)\n",
+      "dp = pr/100*p;    #Uncertainty in momentum(kg-m/s)\n",
+      "h_bar = h/(2*math.pi);     #Reduced Planck's constant(Js)\n",
+      "dx = h_bar/(2*dp);         #Uncertainty in position(m)\n",
+      "\n",
+      "#Result\n",
+      "print \"The uncertainty in position of electron is\",dx, \"m\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The uncertainty in position of electron is 5.26175358211e-08 m\n"
+       ]
+      }
+     ],
+     "prompt_number": 3
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 9.5, Page number 203"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "e = 1.6*10**-19;     #Energy equivalent of 1 eV(J/eV)\n",
+      "h = 6.626*10**-34;    #Planck's constant(Js)\n",
+      "dt = 10**-8;      #Uncertainty in time(s)\n",
+      "\n",
+      "#Calculation\n",
+      "h_bar = h/(2*math.pi);    #Reduced Planck's constant(Js)\n",
+      "dE = h_bar/(2*dt*e);       #Uncertainty in energy of the excited state(m)\n",
+      "\n",
+      "#Result\n",
+      "print \"The uncertainty in energy of the excited state is\",dE, \"eV\"\n",
+      "\n",
+      "#answer given in the book is wrong"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The uncertainty in energy of the excited state is 3.2955020404e-08 eV\n"
+       ]
+      }
+     ],
+     "prompt_number": 4
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 9.6, Page number 204"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "\n",
+      "#Variable declaration\n",
+      "c = 3*10**8;      #Speed of light(m/s)\n",
+      "dt = 10**-8;      #Average lifetime(s)\n",
+      "lamda = 400;    #Wavelength of spectral line(nm)\n",
+      "\n",
+      "#Calculation\n",
+      "lamda = lamda*10**-9;      #Wavelength of spectral line(m)\n",
+      "#From Heisenberg uncertainty principle,\n",
+      "#dE = h_bar/(2*dt) and also dE = h*c/lambda^2*d_lambda, which give\n",
+      "#h_bar/(2*dt) = h*c/lambda^2*d_lambda, solving for d_lambda\n",
+      "d_lamda = (lamda**2)/(4*math.pi*c*dt);     #Width of spectral line(m)\n",
+      "\n",
+      "#Result\n",
+      "print \"The width of spectral line is\",d_lamda, \"m\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The width of spectral line is 4.24413181578e-15 m\n"
+       ]
+      }
+     ],
+     "prompt_number": 5
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 9.7, Page number 204. theoritical proof"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 9.8, Page number 204. theoritical proof"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 9.9, Page number 205. theoritical proof"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 9.10, Page number 205. theoritical proof"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 9.11, Page number 205. theoritical proof"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 9.12, Page number 206. theoritical proof"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 9.13, Page number 206. theoritical proof "
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example number 9.14, Page number 207"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "\n",
+      "#importing modules\n",
+      "import math\n",
+      "from __future__ import division\n",
+      "from scipy.integrate import quad\n",
+      "\n",
+      "#Variable declaration\n",
+      "a = 2*10**-10;    # Width of 1D box(m)\n",
+      "x1=0;    # Position of first extreme of the box(m)\n",
+      "x2=1*10**-10;   # Position of second extreme of the box(m)\n",
+      "\n",
+      "#Calculation\n",
+      "def intg(x):\n",
+      "    return ((2/a)*(math.sin(2*math.pi*x/a))**2)\n",
+      "S=quad(intg,x1,x2)[0]\n",
+      "\n",
+      "#Result\n",
+      "print \"The probability of finding the electron between x = 0 and x = 10**-10 is\",S"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The probability of finding the electron between x = 0 and x = 10**-10 is 0.5\n"
+       ]
+      }
+     ],
+     "prompt_number": 7
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [],
+     "language": "python",
+     "metadata": {},
+     "outputs": []
+    }
+   ],
+   "metadata": {}
+  }
+ ]
+}
\ No newline at end of file
diff --git a/Engineering_Physics_by_G._Aruldhas/README.txt b/Engineering_Physics_by_G._Aruldhas/README.txt
new file mode 100755
index 00000000..77c00324
--- /dev/null
+++ b/Engineering_Physics_by_G._Aruldhas/README.txt
@@ -0,0 +1,10 @@
+Contributed By: KRISHNA CHAITANYA
+Course: btech
+College/Institute/Organization: JNTUH
+Department/Designation: Computer Science
+Book Title: Engineering Physics
+Author: G. Aruldhas
+Publisher: PHI Learning ( New Delhi )
+Year of publication: 2012
+Isbn: 9788120339163
+Edition: 2
\ No newline at end of file
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