Added(A)/Deleted(D) following books

 A  BSc_3rd_Year_Physics_Paper_4_by_Sanjeeva_Rao,_Bhikshmaiah,_Ramakrishna_Reddy,_Ananta_Ramaiah/Chapter1.ipynb
A  BSc_3rd_Year_Physics_Paper_4_by_Sanjeeva_Rao,_Bhikshmaiah,_Ramakrishna_Reddy,_Ananta_Ramaiah/Chapter10.ipynb
A  BSc_3rd_Year_Physics_Paper_4_by_Sanjeeva_Rao,_Bhikshmaiah,_Ramakrishna_Reddy,_Ananta_Ramaiah/Chapter11.ipynb
A  BSc_3rd_Year_Physics_Paper_4_by_Sanjeeva_Rao,_Bhikshmaiah,_Ramakrishna_Reddy,_Ananta_Ramaiah/Chapter12.ipynb
A  BSc_3rd_Year_Physics_Paper_4_by_Sanjeeva_Rao,_Bhikshmaiah,_Ramakrishna_Reddy,_Ananta_Ramaiah/Chapter13.ipynb
A  BSc_3rd_Year_Physics_Paper_4_by_Sanjeeva_Rao,_Bhikshmaiah,_Ramakrishna_Reddy,_Ananta_Ramaiah/Chapter14.ipynb
A  BSc_3rd_Year_Physics_Paper_4_by_Sanjeeva_Rao,_Bhikshmaiah,_Ramakrishna_Reddy,_Ananta_Ramaiah/Chapter15.ipynb
A  BSc_3rd_Year_Physics_Paper_4_by_Sanjeeva_Rao,_Bhikshmaiah,_Ramakrishna_Reddy,_Ananta_Ramaiah/Chapter2.ipynb
A  BSc_3rd_Year_Physics_Paper_4_by_Sanjeeva_Rao,_Bhikshmaiah,_Ramakrishna_Reddy,_Ananta_Ramaiah/Chapter3.ipynb
A  BSc_3rd_Year_Physics_Paper_4_by_Sanjeeva_Rao,_Bhikshmaiah,_Ramakrishna_Reddy,_Ananta_Ramaiah/Chapter4.ipynb
A  BSc_3rd_Year_Physics_Paper_4_by_Sanjeeva_Rao,_Bhikshmaiah,_Ramakrishna_Reddy,_Ananta_Ramaiah/Chapter5.ipynb
A  BSc_3rd_Year_Physics_Paper_4_by_Sanjeeva_Rao,_Bhikshmaiah,_Ramakrishna_Reddy,_Ananta_Ramaiah/Chapter6.ipynb
A  BSc_3rd_Year_Physics_Paper_4_by_Sanjeeva_Rao,_Bhikshmaiah,_Ramakrishna_Reddy,_Ananta_Ramaiah/Chapter7.ipynb
A  BSc_3rd_Year_Physics_Paper_4_by_Sanjeeva_Rao,_Bhikshmaiah,_Ramakrishna_Reddy,_Ananta_Ramaiah/Chapter8.ipynb
A  BSc_3rd_Year_Physics_Paper_4_by_Sanjeeva_Rao,_Bhikshmaiah,_Ramakrishna_Reddy,_Ananta_Ramaiah/Chapter9.ipynb
A  BSc_3rd_Year_Physics_Paper_4_by_Sanjeeva_Rao,_Bhikshmaiah,_Ramakrishna_Reddy,_Ananta_Ramaiah/screenshots/11.png
A  BSc_3rd_Year_Physics_Paper_4_by_Sanjeeva_Rao,_Bhikshmaiah,_Ramakrishna_Reddy,_Ananta_Ramaiah/screenshots/22.png
A  BSc_3rd_Year_Physics_Paper_4_by_Sanjeeva_Rao,_Bhikshmaiah,_Ramakrishna_Reddy,_Ananta_Ramaiah/screenshots/33.png
A  Modern_physics_for_engineers_by_S.P.Taneja/AppendixB.ipynb
A  Modern_physics_for_engineers_by_S.P.Taneja/AppendixC.ipynb
A  Modern_physics_for_engineers_by_S.P.Taneja/AppendixE.ipynb
A  Modern_physics_for_engineers_by_S.P.Taneja/Chapter18.ipynb
A  Modern_physics_for_engineers_by_S.P.Taneja/chapter1.ipynb
A  Modern_physics_for_engineers_by_S.P.Taneja/chapter10.ipynb
A  Modern_physics_for_engineers_by_S.P.Taneja/chapter11.ipynb
A  Modern_physics_for_engineers_by_S.P.Taneja/chapter12.ipynb
A  Modern_physics_for_engineers_by_S.P.Taneja/chapter14.ipynb
A  Modern_physics_for_engineers_by_S.P.Taneja/chapter15.ipynb
A  Modern_physics_for_engineers_by_S.P.Taneja/chapter17.ipynb
A  Modern_physics_for_engineers_by_S.P.Taneja/chapter19.ipynb
A  Modern_physics_for_engineers_by_S.P.Taneja/chapter2.ipynb
A  Modern_physics_for_engineers_by_S.P.Taneja/chapter20.ipynb
A  Modern_physics_for_engineers_by_S.P.Taneja/chapter21.ipynb
A  Modern_physics_for_engineers_by_S.P.Taneja/chapter23.ipynb
A  Modern_physics_for_engineers_by_S.P.Taneja/chapter24.ipynb
A  Modern_physics_for_engineers_by_S.P.Taneja/chapter4.ipynb
A  Modern_physics_for_engineers_by_S.P.Taneja/chapter5.ipynb
A  Modern_physics_for_engineers_by_S.P.Taneja/chapter6.ipynb
A  Modern_physics_for_engineers_by_S.P.Taneja/chapter7.ipynb
A  Modern_physics_for_engineers_by_S.P.Taneja/chapter8.ipynb
A  Modern_physics_for_engineers_by_S.P.Taneja/chapter9.ipynb
A  Modern_physics_for_engineers_by_S.P.Taneja/chpater3.ipynb
A  Modern_physics_for_engineers_by_S.P.Taneja/screenshots/image1.png
A  Modern_physics_for_engineers_by_S.P.Taneja/screenshots/image2.png
A  Modern_physics_for_engineers_by_S.P.Taneja/screenshots/image3.png
A  Solid_State_Physics_by_Dr_M_Arumugam/Chapter1.ipynb
A  Solid_State_Physics_by_Dr_M_Arumugam/Chapter10.ipynb
A  Solid_State_Physics_by_Dr_M_Arumugam/Chapter11.ipynb
A  Solid_State_Physics_by_Dr_M_Arumugam/Chapter12.ipynb
A  Solid_State_Physics_by_Dr_M_Arumugam/Chapter13.ipynb
A  Solid_State_Physics_by_Dr_M_Arumugam/Chapter14.ipynb
A  Solid_State_Physics_by_Dr_M_Arumugam/Chapter2.ipynb
A  Solid_State_Physics_by_Dr_M_Arumugam/Chapter3.ipynb
A  Solid_State_Physics_by_Dr_M_Arumugam/Chapter4.ipynb
A  Solid_State_Physics_by_Dr_M_Arumugam/Chapter5.ipynb
A  Solid_State_Physics_by_Dr_M_Arumugam/Chapter6.ipynb
A  Solid_State_Physics_by_Dr_M_Arumugam/Chapter8.ipynb
A  Solid_State_Physics_by_Dr_M_Arumugam/screenshots/22.png
A  Solid_State_Physics_by_Dr_M_Arumugam/screenshots/33.png
A  Solid_State_Physics_by_Dr_M_Arumugam/screenshots/44.png

15 files changed, 3285 insertions, 0 deletions

diff --git a/Solid_State_Physics_by_Dr_M_Arumugam/Chapter1.ipynb b/Solid_State_Physics_by_Dr_M_Arumugam/Chapter1.ipynb
new file mode 100644
index 00000000..7770f9a6
--- /dev/null
+++ b/Solid_State_Physics_by_Dr_M_Arumugam/Chapter1.ipynb
@@ -0,0 +1,151 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# 1: Bonding in Solids"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 1, Page number 1.21"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 6,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "-2*a/r**3 + 90*b/r**11\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "from sympy import diff,Symbol\n",
+    "import numpy as np\n",
+    "\n",
+    "#Variable declaration\n",
+    "n=1;\n",
+    "m=9;\n",
+    "a=Symbol('a')\n",
+    "b=Symbol('b')\n",
+    "r=Symbol('r')\n",
+    "\n",
+    "#Calculation\n",
+    "y=(-a/(r**n))+(b/(r**m));\n",
+    "y=diff(y,r);\n",
+    "y=diff(y,r);\n",
+    "\n",
+    "#Result\n",
+    "print y"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 6,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "young's modulus is 157 GPa\n"
+     ]
+    }
+   ],
+   "source": [
+    "#since the values of a,b,r are declared as symbols in the above cell, it cannot be solved there. hence it is being solved here with the given variable declaration\n",
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "a=7.68*10**-29;     \n",
+    "r0=2.5*10**-10;    #radius(m)\n",
+    "\n",
+    "#Calculation\n",
+    "b=a*(r0**8)/9;\n",
+    "y=((-2*a*r0**8)+(90*b))/r0**11;    \n",
+    "E=y/r0;           #young's modulus(Pa)\n",
+    "\n",
+    "#Result\n",
+    "print \"young's modulus is\",int(E/10**9),\"GPa\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 2, Page number 1.22"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 7,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "effective charge is 0.72 *10**-19 coulomb\n",
+      "answer given in the book is wrong\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "dm=1.98*10**-29/3;      #dipole moment\n",
+    "l=0.92*10**-10;         #bond length(m)\n",
+    "\n",
+    "#Calculation\n",
+    "ec=dm/l;        #effective charge(coulomb)\n",
+    "\n",
+    "#Result\n",
+    "print \"effective charge is\",round(ec*10**19,2),\"*10**-19 coulomb\"\n",
+    "print \"answer given in the book is wrong\""
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.11"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/Solid_State_Physics_by_Dr_M_Arumugam/Chapter10.ipynb b/Solid_State_Physics_by_Dr_M_Arumugam/Chapter10.ipynb
new file mode 100644
index 00000000..76c25efb
--- /dev/null
+++ b/Solid_State_Physics_by_Dr_M_Arumugam/Chapter10.ipynb
@@ -0,0 +1,212 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# 10: Dielectric Properties"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 1, Page number 10.26"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "insulation resistance is 0.85 *10**18 ohm\n",
+      "answer varies due to rounding off errors\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "rho=5*10**16;   #resistivity(ohm m)\n",
+    "l=5*10**-2;    #thickness(m)\n",
+    "b=8*10**-2;    #length(m)\n",
+    "w=3*10**-2;    #width(m)\n",
+    "\n",
+    "#Calculation\n",
+    "A=b*w;    #area(m**2)\n",
+    "Rv=rho*l/A;    \n",
+    "X=l+b;      #length(m)\n",
+    "Y=w;      #perpendicular(m)\n",
+    "Rs=Rv*X/Y;    \n",
+    "Ri=Rs*Rv/(Rs+Rv);       #insulation resistance(ohm)\n",
+    "\n",
+    "#Result\n",
+    "print \"insulation resistance is\",round(Ri/10**18,2),\"*10**18 ohm\"\n",
+    "print \"answer varies due to rounding off errors\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 2, Page number 10.26"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 4,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "polarisability of He is 0.185 *10**-40 farad m**2\n",
+      "relative permittivity is 1.0000564\n",
+      "answer varies due to rounding off errors\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "epsilon0=8.84*10**-12;\n",
+    "R=0.55*10**-10;    #radius(m)\n",
+    "N=2.7*10**25;      #number of atoms\n",
+    "\n",
+    "#Calculation\n",
+    "alpha_e=4*math.pi*epsilon0*R**3;    #polarisability of He(farad m**2)\n",
+    "epsilonr=1+(N*alpha_e/epsilon0);      #relative permittivity\n",
+    "\n",
+    "#Result\n",
+    "print \"polarisability of He is\",round(alpha_e*10**40,3),\"*10**-40 farad m**2\"\n",
+    "print \"relative permittivity is\",round(epsilonr,7)\n",
+    "print \"answer varies due to rounding off errors\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 3, Page number 10.27"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 5,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "field strength is 3.535 *10**7 V/m\n",
+      "total dipole moment is 33.4 *10**-12 Cm\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "A=360*10**-4;    #area(m**2)\n",
+    "V=15;    #voltage(V)\n",
+    "C=6*10**-6;     #capacitance(farad)\n",
+    "epsilonr=8;\n",
+    "epsilon0=8.84*10**-12;\n",
+    "\n",
+    "#Calculation\n",
+    "E=V*C/(epsilon0*epsilonr*A);     #field strength(V/m)\n",
+    "dm=epsilon0*(epsilonr-1)*V*A;    #total dipole moment(Cm)\n",
+    "\n",
+    "#Result\n",
+    "print \"field strength is\",round(E/10**7,3),\"*10**7 V/m\"\n",
+    "print \"total dipole moment is\",round(dm*10**12,1),\"*10**-12 Cm\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 4, Page number 10.27"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 7,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "the complex polarizability is (3.50379335033-0.0600074383321j) *10**-40 F-m**2\n",
+      "answer cant be rouned off to 2 decimals as given in the textbook. Since it is a complex number and complex numbers cant be converted to float\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "epsilonr=4.36;      #dielectric constant\n",
+    "t=2.8*10**-2;       #loss tangent(t)\n",
+    "N=4*10**28;         #number of electrons\n",
+    "epsilon0=8.84*10**-12;      \n",
+    "\n",
+    "#Calculation\n",
+    "epsilon_r = epsilonr*t;\n",
+    "epsilonstar = (complex(epsilonr,-epsilon_r));\n",
+    "alphastar = (epsilonstar-1)/(epsilonstar+2);\n",
+    "alpha_star = 3*epsilon0*alphastar/N;             #complex polarizability(Fm**2)\n",
+    "\n",
+    "#Result\n",
+    "print \"the complex polarizability is\",alpha_star*10**40,\"*10**-40 F-m**2\"\n",
+    "print \"answer cant be rouned off to 2 decimals as given in the textbook. Since it is a complex number and complex numbers cant be converted to float\""
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.11"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/Solid_State_Physics_by_Dr_M_Arumugam/Chapter11.ipynb b/Solid_State_Physics_by_Dr_M_Arumugam/Chapter11.ipynb
new file mode 100644
index 00000000..617a2a18
--- /dev/null
+++ b/Solid_State_Physics_by_Dr_M_Arumugam/Chapter11.ipynb
@@ -0,0 +1,327 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# 11: Magnetic Properties"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 1, Page number 11.31"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "temperature rise is 8.43 K\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "El=10**-2*50;       #energy loss(J)\n",
+    "H=El*60;      #heat produced(J)\n",
+    "d=7.7*10**3;    #iron rod(kg/m**3)\n",
+    "s=0.462*10**-3;    #specific heat(J/kg K)\n",
+    "\n",
+    "#Calculation\n",
+    "theta=H/(d*s);     #temperature rise(K)\n",
+    "\n",
+    "#Result\n",
+    "print \"temperature rise is\",round(theta,2),\"K\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 2, Page number 11.31"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 4,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "magnetic field at the centre is 14 weber/m**2\n",
+      "dipole moment is 9 *10**-24 ampere/m**2\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "e=1.6*10**-19;    #charge(coulomb)\n",
+    "new=6.8*10**15;   #frequency(revolutions per second)\n",
+    "mew0=4*math.pi*10**-7;\n",
+    "R=5.1*10**-11;     #radius(m)\n",
+    "\n",
+    "#Calculation\n",
+    "i=round(e*new,4);          #current(ampere)\n",
+    "B=mew0*i/(2*R);    #magnetic field at the centre(weber/m**2)\n",
+    "A=math.pi*R**2;\n",
+    "d=i*A;       #dipole moment(ampere/m**2)\n",
+    "\n",
+    "#Result\n",
+    "print \"magnetic field at the centre is\",int(round(B)),\"weber/m**2\"\n",
+    "print \"dipole moment is\",int(round(d*10**24)),\"*10**-24 ampere/m**2\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 3, Page number 11.31"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 6,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "intensity of magnetisation is 5 ampere/m\n",
+      "flux density in material is 1.257 weber/m**2\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "chi=0.5*10**-5;    #magnetic susceptibility\n",
+    "H=10**6;     #field strength(ampere/m)\n",
+    "mew0=4*math.pi*10**-7;\n",
+    "\n",
+    "#Calculation\n",
+    "I=chi*H;     #intensity of magnetisation(ampere/m)\n",
+    "B=mew0*(I+H);    #flux density in material(weber/m**2)\n",
+    "\n",
+    "#Result\n",
+    "print \"intensity of magnetisation is\",int(I),\"ampere/m\"\n",
+    "print \"flux density in material is\",round(B,3),\"weber/m**2\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 4, Page number 11.31"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 7,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "number of Bohr magnetons is 2.22 bohr magneon/atom\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "B=9.27*10**-24;      #bohr magneton(ampere m**2)\n",
+    "a=2.86*10**-10;      #edge(m)\n",
+    "Is=1.76*10**6;       #saturation value of magnetisation(ampere/m)\n",
+    "\n",
+    "#Calculation\n",
+    "N=2/a**3;\n",
+    "mew_bar=Is/N;      #number of Bohr magnetons(ampere m**2)\n",
+    "mew_bar=mew_bar/B;      #number of Bohr magnetons(bohr magneon/atom)\n",
+    "\n",
+    "#Result\n",
+    "print \"number of Bohr magnetons is\",round(mew_bar,2),\"bohr magneon/atom\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 5, Page number 11.32"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 8,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "average magnetic moment is 2.79 *10**-3 bohr magneton/spin\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "mew0=4*math.pi*10**-7;\n",
+    "H=9.27*10**-24;      #bohr magneton(ampere m**2)\n",
+    "beta=10**6;      #field(ampere/m)\n",
+    "k=1.38*10**-23;    #boltzmann constant\n",
+    "T=303;    #temperature(K)\n",
+    "\n",
+    "#Calculation\n",
+    "mm=mew0*H*beta/(k*T);    #average magnetic moment(bohr magneton/spin)\n",
+    "\n",
+    "#Result\n",
+    "print \"average magnetic moment is\",round(mm*10**3,2),\"*10**-3 bohr magneton/spin\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 6, Page number 11.32"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 11,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "hysteresis loss per cycle is 188 J/m**3\n",
+      "hysteresis loss per second is 9400 watt/m**3\n",
+      "power loss is 1.23 watt/kg\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "A=94;      #area(m**2)\n",
+    "vy=0.1;    #value of length(weber/m**2)\n",
+    "vx=20;     #value of unit length\n",
+    "n=50;      #number of magnetization cycles\n",
+    "d=7650;    #density(kg/m**3)\n",
+    "\n",
+    "#Calculation\n",
+    "h=A*vy*vx;     #hysteresis loss per cycle(J/m**3)\n",
+    "hs=h*n;       #hysteresis loss per second(watt/m**3)\n",
+    "pl=hs/d;      #power loss(watt/kg)\n",
+    "\n",
+    "#Result\n",
+    "print \"hysteresis loss per cycle is\",int(h),\"J/m**3\"\n",
+    "print \"hysteresis loss per second is\",int(hs),\"watt/m**3\"\n",
+    "print \"power loss is\",round(pl,2),\"watt/kg\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 8, Page number 11.33"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 13,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "critical field is 33.64 *10**3 ampere/m\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "H0=64*10**3;         #initial field(ampere/m)\n",
+    "T=5;                 #temperature(K)\n",
+    "Tc=7.26;             #critical temperature(K)\n",
+    "\n",
+    "#Calculation\n",
+    "H=H0*(1-(T/Tc)**2);      #critical field(ampere/m)\n",
+    "\n",
+    "#Result\n",
+    "print \"critical field is\",round(H/10**3,2),\"*10**3 ampere/m\""
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.11"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/Solid_State_Physics_by_Dr_M_Arumugam/Chapter12.ipynb b/Solid_State_Physics_by_Dr_M_Arumugam/Chapter12.ipynb
new file mode 100644
index 00000000..af17168c
--- /dev/null
+++ b/Solid_State_Physics_by_Dr_M_Arumugam/Chapter12.ipynb
@@ -0,0 +1,160 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# 12: Lasers"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 1, Page number 12.30"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 5,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "relative population in laser transition levels is 1.081 *10**30\n",
+      "answer given in the book is wrong\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "h=6.626*10**-34;       #plancks constant(J s)\n",
+    "c=3*10**8;             #velocity of light(m/s)\n",
+    "lamda=6943*10**-10;    #wavelength of emission(m)\n",
+    "k=1.38*10**-23;        #boltzmann constant\n",
+    "T=300;                 #temperature(K)\n",
+    "\n",
+    "#Calculation\n",
+    "new=c/lamda;           #frequency(Hz)\n",
+    "x=h*new/(k*T);\n",
+    "N1byN2=math.exp(x);    #relative population in laser transition levels\n",
+    "\n",
+    "#Result\n",
+    "print \"relative population in laser transition levels is\",round(N1byN2/10**30,3),\"*10**30\"\n",
+    "print \"answer given in the book is wrong\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 2, Page number 12.31"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 10,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "number of photons emitted is 7.323 *10**15 photons/second\n",
+      "power density is 2.3 kW/m**2\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "h=6.626*10**-34;       #plancks constant(J s)\n",
+    "P=2.3*10**-3;          #output power(W)\n",
+    "t=1;                   #time(sec)\n",
+    "new=4.74*10**14;       #frequency(Hz)\n",
+    "s=1*10**-6;            #spot area(m**2)\n",
+    "\n",
+    "#Calculation\n",
+    "n=P*t/(h*new);         #number of photons emitted in each second \n",
+    "Pd=P/s;                #power density(W/m**2)\n",
+    "\n",
+    "#Result\n",
+    "print \"number of photons emitted is\",round(n/10**15,3),\"*10**15 photons/second\"\n",
+    "print \"power density is\",Pd/10**3,\"kW/m**2\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 3, Page number 12.31"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "wavelength of emission is 8628 angstrom\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "h=6.626*10**-34;       #plancks constant(J s)\n",
+    "c=3*10**8;     #velocity of light(m/s)\n",
+    "Eg=1.44*1.6*10**-19;    #band gap(J)\n",
+    "\n",
+    "#Calculation\n",
+    "lamda=h*c/Eg;      #wavelength of emission(m)\n",
+    "\n",
+    "#Result\n",
+    "print \"wavelength of emission is\",int(round(lamda*10**10)),\"angstrom\""
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.11"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/Solid_State_Physics_by_Dr_M_Arumugam/Chapter13.ipynb b/Solid_State_Physics_by_Dr_M_Arumugam/Chapter13.ipynb
new file mode 100644
index 00000000..558f6667
--- /dev/null
+++ b/Solid_State_Physics_by_Dr_M_Arumugam/Chapter13.ipynb
@@ -0,0 +1,665 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# 13: Fiber Optics"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 1, Page number 13.19"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "critical angle is 78.5 degrees\n",
+      "numerical aperture is 0.3\n",
+      "acceptance angle is 17.4 degrees\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "n2=1.47;              #refractive index of cladding\n",
+    "n1=1.5;    #refractive index of core\n",
+    "\n",
+    "#Calculation\n",
+    "phi_c=math.asin(n2/n1);     #critical angle(radian)\n",
+    "phi_c=phi_c*180/math.pi;    #critical angle(degrees)\n",
+    "NA=math.sqrt(n1**2-n2**2);     #numerical aperture\n",
+    "phi_max=math.asin(NA);       #acceptance angle(radian)\n",
+    "phi_max=phi_max*180/math.pi;    #acceptance angle(degrees)\n",
+    "\n",
+    "#Result\n",
+    "print \"critical angle is\",round(phi_c,1),\"degrees\"\n",
+    "print \"numerical aperture is\",round(NA,1)\n",
+    "print \"acceptance angle is\",round(phi_max,1),\"degrees\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 2, Page number 13.19"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 4,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "total number of guided modes is 490\n",
+      "number of modes propagated inside fibre is 245\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "d=50*10**-6;     #diameter(m)\n",
+    "NA=0.2;      #numerical aperture(m)\n",
+    "lamda=1*10**-6;    #wavelength(m)\n",
+    "\n",
+    "#Calculation\n",
+    "N=4.9*(d*NA/lamda)**2;     #total number of guided modes\n",
+    "Nf=N/2;                    #number of modes propagated inside fibre\n",
+    "\n",
+    "#Result\n",
+    "print \"total number of guided modes is\",int(N)\n",
+    "print \"number of modes propagated inside fibre is\",int(Nf)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 3, Page number 13.19"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 6,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "total number of guided modes is 1\n",
+      "it is a single mode propagation\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "d=5*10**-6;     #diameter(m)\n",
+    "n2=1.447;              #refractive index of cladding\n",
+    "n1=1.45;    #refractive index of core\n",
+    "lamda=1*10**-6;    #wavelength(m)\n",
+    "\n",
+    "#Calculation\n",
+    "NA=math.sqrt(n1**2-n2**2);      #numerical aperture\n",
+    "N=4.9*(d*NA/lamda)**2;     #total number of guided modes\n",
+    "\n",
+    "#Result\n",
+    "print \"total number of guided modes is\",int(N)\n",
+    "print \"it is a single mode propagation\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 4, Page number 13.19"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 7,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "numerical aperture is 0.46\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "n1=1.46;    #refractive index of core\n",
+    "delta=0.05;    #refractive index difference\n",
+    "\n",
+    "#Calculation\n",
+    "NA=n1*math.sqrt(2*delta);     #numerical aperture\n",
+    "\n",
+    "#Result\n",
+    "print \"numerical aperture is\",round(NA,2)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 5, Page number 13.20"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 9,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "V number is 94.72\n",
+      "maximum number of modes is 4486\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "a=50;\n",
+    "n2=1.5;              #refractive index of cladding\n",
+    "n1=1.53;    #refractive index of core\n",
+    "lamda0=1;    #wavelength(micro m)\n",
+    "\n",
+    "#Calculation\n",
+    "V_number=round(2*math.pi*a*math.sqrt(n1**2-n2**2)/lamda0,2);     #V number\n",
+    "n=V_number**2/2;     #maximum number of modes\n",
+    "\n",
+    "#Result\n",
+    "print \"V number is\",V_number\n",
+    "print \"maximum number of modes is\",int(round(n))"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 6, Page number 13.20"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 11,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "total number of modes is 49178\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "a=100*10**-6;\n",
+    "NA=0.3;      #numerical aperture(m)\n",
+    "lamda=850*10**-9;    #wavelength(m)\n",
+    "\n",
+    "#Calculation\n",
+    "V_number=round(2*math.pi**2*a**2*NA**2/lamda**2);     #number of modes\n",
+    "\n",
+    "#Result\n",
+    "print \"total number of modes is\",int(2*V_number)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 7, Page number 13.20"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 12,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "cutoff wavelength is 1.315 micro m\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "a=25*10**-6;\n",
+    "n1=1.48;    #refractive index of core\n",
+    "delta=0.01;    #refractive index difference\n",
+    "V=25;     #Vnumber\n",
+    "\n",
+    "#Calculation\n",
+    "lamda=2*math.pi*a*n1*math.sqrt(2*delta)/V;      #cutoff wavelength(m)\n",
+    "\n",
+    "#Result\n",
+    "print \"cutoff wavelength is\",round(lamda*10**6,3),\"micro m\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 8, Page number 13.20"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 14,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "maximum value of core radius is 9.95 micro m\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "V=2.405;     #Vnumber\n",
+    "lamda=1.3;    #wavelength(micro m)\n",
+    "NA=0.05;      #numerical aperture(m)\n",
+    "\n",
+    "#Calculation\n",
+    "amax=V*lamda/(2*math.pi*NA);     #maximum value of core radius(micro m)\n",
+    "\n",
+    "#Result\n",
+    "print \"maximum value of core radius is\",round(amax,2),\"micro m\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 9, Page number 13.21"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 17,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "acceptance angle for meridional rays is 17.46 degrees\n",
+      "acceptance angle for skew rays is 25.104 degrees\n",
+      "answer for acceptance angle for skew rays given in the book is wrong\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "NA=0.3;      #numerical aperture(m)\n",
+    "gama=45*math.pi/180;     #angle(radian)\n",
+    "\n",
+    "#Calculation\n",
+    "thetaa=math.asin(NA);       #acceptance angle for meridional rays(radian)\n",
+    "thetaa=thetaa*180/math.pi;  #acceptance angle for meridional rays(degrees)\n",
+    "thetaas=math.asin(NA/math.cos(gama));     #acceptance angle for skew rays(radian)\n",
+    "thetaas=thetaas*180/math.pi;   #acceptance angle for skew rays(degrees)\n",
+    "\n",
+    "#Result\n",
+    "print \"acceptance angle for meridional rays is\",round(thetaa,2),\"degrees\"\n",
+    "print \"acceptance angle for skew rays is\",round(thetaas,3),\"degrees\"\n",
+    "print \"answer for acceptance angle for skew rays given in the book is wrong\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 10, Page number 13.21"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 22,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "numerical aperture is 0.303\n",
+      "acceptance angle is 17.633 degrees\n",
+      "answer for angle given in the book varies due to rounding off errors\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "delta=0.0196;         #relative refractive index difference\n",
+    "n1=1.53;              #refractive index of core\n",
+    "\n",
+    "#Calculation\n",
+    "NA=n1*math.sqrt(2*delta);     #numerical aperture\n",
+    "theta=math.asin(NA);          #acceptance angle(radian)\n",
+    "theta=theta*180/math.pi;      #acceptance angle(degrees)\n",
+    "\n",
+    "#Result\n",
+    "print \"numerical aperture is\",round(NA,3)\n",
+    "print \"acceptance angle is\",round(theta,3),\"degrees\"\n",
+    "print \"answer for angle given in the book varies due to rounding off errors\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 11, Page number 13.21"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 25,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "core radius is 1.548 micro m\n",
+      "answer given in the book is wrong\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "n2=1.465;             #refractive index of cladding\n",
+    "n1=1.480;             #refractive index of core\n",
+    "lamda=850*10**-9;     #wavelength(m)\n",
+    "\n",
+    "#Calculation\n",
+    "delta=(n1**2-n2**2)/(2*n1**2);         #relative refractive index difference\n",
+    "a=2.405*lamda*10**6/(2*math.pi*n1*math.sqrt(2*delta));     #core radius(micro m)\n",
+    "\n",
+    "#Result\n",
+    "print \"core radius is\",round(a,3),\"micro m\"\n",
+    "print \"answer given in the book is wrong\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 12, Page number 13.21"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 32,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "total number of reflections per metre is 2321\n",
+      "total distance travelled by light is 1.0067 m\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "n2=1.49;             #refractive index of cladding\n",
+    "n1=1.5;              #refractive index of core\n",
+    "a=25;                #core radius(micro m)\n",
+    "\n",
+    "#Calculation\n",
+    "phic=math.asin(n2/n1);                  #angle(degrees)\n",
+    "l=2*a*math.tan(phic);                   #fibre length covered in 1 reflection(micro m)\n",
+    "n=10**6/l;                              #total number of reflections per metre\n",
+    "d=1/math.sin(phic);                     #total distance travelled by light(m)\n",
+    "\n",
+    "#Result\n",
+    "print \"total number of reflections per metre is\",int(n)\n",
+    "print \"total distance travelled by light is\",round(d,4),\"m\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 13, Page number 13.22"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 36,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "total number of modes is 309\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "alpha=1.85;          #index profile\n",
+    "a=25;                #core radius(micro m)\n",
+    "NA=0.21;             #numerical aperture\n",
+    "lamda=1.3;           #wavelength(micro m)\n",
+    "\n",
+    "#Calculation\n",
+    "n=(alpha*2*math.pi**2*a**2*NA**2)/(lamda**2*(alpha+2));     #number of modes\n",
+    "N=2*n;               #total number of modes\n",
+    "\n",
+    "#Result\n",
+    "print \"total number of modes is\",int(N)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 14, Page number 13.22"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 41,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "signal attenuation per unit length is 1.7 dB km-1\n",
+      "overall signal attenuation is 17 dB\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "L=10;        #transmission distance(km)\n",
+    "Pi=100;      #optical power(micro W)\n",
+    "Po=2;        #optical power output(micro W)\n",
+    "\n",
+    "#Calculation\n",
+    "sa=round(10*math.log10(Pi/Po)/L,1);     #signal attenuation per unit length(dB km-1)\n",
+    "osa=sa*L;                    #overall signal attenuation(dB)\n",
+    "\n",
+    "#Result\n",
+    "print \"signal attenuation per unit length is\",sa,\"dB km-1\"\n",
+    "print \"overall signal attenuation is\",int(osa),\"dB\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 15, Page number 13.23"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 51,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "dispersion is 1343.3 ns\n",
+      "bandwidth length product is 7.44 *10**6 Hz-km\n",
+      "answer for bandwidth given in the book is wrong\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "L=10;        #transmission distance(km)\n",
+    "n1=1.55;     #refractive index of core\n",
+    "delta=0.026;  #relative refractive index difference\n",
+    "C=3*10**5;    \n",
+    "\n",
+    "#Calculation\n",
+    "deltaT=L*n1*delta/C;    #dispersion(s)\n",
+    "blp=L/deltaT;           #bandwidth length product(Hz-km)\n",
+    "\n",
+    "#Result\n",
+    "print \"dispersion is\",round(deltaT*10**9,1),\"ns\"\n",
+    "print \"bandwidth length product is\",round(blp/10**6,2),\"*10**6 Hz-km\"\n",
+    "print \"answer for bandwidth given in the book is wrong\""
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.11"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/Solid_State_Physics_by_Dr_M_Arumugam/Chapter14.ipynb b/Solid_State_Physics_by_Dr_M_Arumugam/Chapter14.ipynb
new file mode 100644
index 00000000..92fbeef0
--- /dev/null
+++ b/Solid_State_Physics_by_Dr_M_Arumugam/Chapter14.ipynb
@@ -0,0 +1,205 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# 14: Acoustics of Buildings and Acoustic Quieting"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 1, Page number 14.18"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 4,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "reverbration time is 3.9 s\n",
+      "reverbration time when audience fill the hall is 1.95 s\n",
+      "reverbration time is reduced to one-half\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "V=2265;      #volume(m**3)\n",
+    "a=92.9;      #absorption(m**2)\n",
+    "\n",
+    "#Calculation\n",
+    "T=0.16*V/a;    #reverbration time(s)\n",
+    "T2=T/2;        #reverbration time when audience fill the hall(s)\n",
+    "\n",
+    "#Result\n",
+    "print \"reverbration time is\",round(T,1),\"s\"\n",
+    "print \"reverbration time when audience fill the hall is\",round(T2,2),\"s\"\n",
+    "print \"reverbration time is reduced to one-half\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 2, Page number 14.18"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 7,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "reverbration time is 0.8 second\n",
+      "reverbration time when hall is empty is 1.6 second\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "V=12*30*6;    #volume(m**3)\n",
+    "A1=450;       #area of plastered wall(m**2)\n",
+    "a1=0.03;      #coefficient of absorption(m**2)\n",
+    "A2=360;       #area of wooden floor(m**2)\n",
+    "a2=0.06;      #coefficient of absorption(m**2)\n",
+    "A3=24;        #area of glass(m**2)\n",
+    "a3=0.25;      #coefficient of absorption(m**2)\n",
+    "A4=600;       #area of seats(m**2)\n",
+    "a4=0.3;       #coefficient of absorption(m**2)\n",
+    "A5=500;       #area of hall with audience(m**2)\n",
+    "a5=0.43;      #coefficient of absorption(m**2)\n",
+    "\n",
+    "#Calculation\n",
+    "A=(A1*a1)+(A2*a2)+(A3*a3)+(A4*a4)+(A5*a5);    #total absorption(m**2)\n",
+    "Ae=A-(A5*a5);                                 #absorption when hall is empty(m**2) \n",
+    "T=0.16*V/A;   #reverbration time(second)\n",
+    "Te=0.16*V/Ae; #reverbration time when hall is empty(second)\n",
+    "\n",
+    "#Result\n",
+    "print \"reverbration time is\",round(T,1),\"second\"\n",
+    "print \"reverbration time when hall is empty is\",round(Te,1),\"second\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 3, Page number 14.19"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 11,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "total absorption is 1000 m**2 or OWU\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "V=7500;    #volume(m**3)\n",
+    "T=1.2;     #reverbration time(second)\n",
+    "\n",
+    "#Calculation\n",
+    "A=0.16*V/T;     #total absorption(OWU)\n",
+    "\n",
+    "#Result\n",
+    "print \"total absorption is\",int(A),\"m**2 or OWU\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 4, Page number 14.19"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 29,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "change in reverbration time is 0.727 second\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "V=12*10**4;      #volume(m**3)\n",
+    "a=13200;         #absorption(m**2)\n",
+    "\n",
+    "#Calculation\n",
+    "T1=0.16*V/a;    #reverbration time(s)\n",
+    "T2=T1/2;         #reverbration time when audience fill the hall(s)\n",
+    "T=T1-T2;        #change in reverbration time(second)\n",
+    "\n",
+    "#Result\n",
+    "print \"change in reverbration time is\",round(T,3),\"second\""
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.11"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/Solid_State_Physics_by_Dr_M_Arumugam/Chapter2.ipynb b/Solid_State_Physics_by_Dr_M_Arumugam/Chapter2.ipynb
new file mode 100644
index 00000000..51d55e0b
--- /dev/null
+++ b/Solid_State_Physics_by_Dr_M_Arumugam/Chapter2.ipynb
@@ -0,0 +1,319 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# 2: Crystallography and Crystal Structures"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 2, Page number 2.21"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "spacing between (100) plane is 5.64 angstrom\n",
+      "spacing between (110) plane is 3.99 angstrom\n",
+      "answer for spacing between (110) plane given in the book is wrong\n",
+      "spacing between (111) plane is 3.26 angstrom\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "a=5.64;      #lattice constant(angstrom)\n",
+    "h1=1;\n",
+    "k1=0;\n",
+    "l1=0;\n",
+    "h2=1;\n",
+    "k2=1;\n",
+    "l2=0;\n",
+    "h3=1;\n",
+    "k3=1;\n",
+    "l3=1;\n",
+    "\n",
+    "#Calculation\n",
+    "d100=a/math.sqrt(h1**2+k1**2+l1**2);     #spacing between (100) plane\n",
+    "d110=a/math.sqrt(h2**2+k2**2+l2**2);     #spacing between (110) plane\n",
+    "d111=a/math.sqrt(h3**2+k3**2+l3**2);     #spacing between (111) plane\n",
+    "\n",
+    "#Result\n",
+    "print \"spacing between (100) plane is\",d100,\"angstrom\"\n",
+    "print \"spacing between (110) plane is\",round(d110,2),\"angstrom\"\n",
+    "print \"answer for spacing between (110) plane given in the book is wrong\"\n",
+    "print \"spacing between (111) plane is\",round(d111,2),\"angstrom\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 3, Page number 2.22"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 8,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "number of atoms in (100) is 1.535 *10**13 atoms/mm**2\n",
+      "number of atoms in (110) is 1.085 *10**13 atoms/mm**2\n",
+      "number of atoms in (111) is 1.772 *10**13 atoms/mm**2\n",
+      "answers given in the book vary due to rounding off errors\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "a=3.61*10**-7;        #lattice constant(mm)\n",
+    "\n",
+    "#Calculation\n",
+    "A100=a**2;     #surface area(mm**2)\n",
+    "n=1+(4*(1/4));\n",
+    "N1=n/A100;      #number of atoms in (100)(per mm**2)\n",
+    "A110=math.sqrt(2)*a**2;      #surface area(mm**2)\n",
+    "N2=n/A110;      #number of atoms in (110)(per mm**2)\n",
+    "A111=math.sqrt(3)*a**2/2;    #surface area(mm**2)\n",
+    "N3=n/A111;     #number of atoms in (110)(per mm**2)\n",
+    "\n",
+    "#Result\n",
+    "print \"number of atoms in (100) is\",round(N1/10**13,3),\"*10**13 atoms/mm**2\"\n",
+    "print \"number of atoms in (110) is\",round(N2/10**13,3),\"*10**13 atoms/mm**2\"\n",
+    "print \"number of atoms in (111) is\",round(N3/10**13,3),\"*10**13 atoms/mm**2\"\n",
+    "print \"answers given in the book vary due to rounding off errors\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 4, Page number 2.23"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 12,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "wavelength of x rays is 1.552 angstrom\n",
+      "answer varies due to rounding off errors\n",
+      "energy of x rays is 8 *10**3 eV\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "n=4;      \n",
+    "A=107.87;    #atomic weight\n",
+    "rho=10500;     #density(kg/m**3)\n",
+    "N=6.02*10**26;    #number of molecules\n",
+    "theta=19+(12/60);   #angle(degrees)\n",
+    "h=1;\n",
+    "k=1;\n",
+    "l=1;\n",
+    "h0=6.625*10**-34;     #planck constant\n",
+    "c=3*10**8;     #velocity of light(m/s)\n",
+    "e=1.6*10**-19;   #charge(coulomb)\n",
+    "\n",
+    "#Calculation\n",
+    "theta=theta*math.pi/180;     #angle(radian)\n",
+    "a=(n*A/(N*rho))**(1/3);\n",
+    "d=a*10**10/math.sqrt(h**2+k**2+l**2);      \n",
+    "lamda=2*d*math.sin(theta);     #wavelength of x rays(angstrom)\n",
+    "E=h0*c/(lamda*10**-10*e);      #energy of x rays(eV)\n",
+    "\n",
+    "#Result\n",
+    "print \"wavelength of x rays is\",round(lamda,3),\"angstrom\"\n",
+    "print \"answer varies due to rounding off errors\"\n",
+    "print \"energy of x rays is\",int(E/10**3),\"*10**3 eV\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 5, Page number 2.23"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 13,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "density is 2332 kg/m**3\n",
+      "answer varies due to rounding off errors\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "n=8;    #number of atoms\n",
+    "r=2.351*10**-10;     #bond length(angstrom)\n",
+    "A=28.09;                #Atomic wt. of NaCl\n",
+    "N=6.02*10**26           #Avagadro number\n",
+    "\n",
+    "#Calculation\n",
+    "a=4*r/math.sqrt(3);     \n",
+    "rho=n*A/(N*a**3);     #density(kg/m**3)\n",
+    "\n",
+    "#Result\n",
+    "print \"density is\",int(rho),\"kg/m**3\"\n",
+    "print \"answer varies due to rounding off errors\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 6, Page number 2.24"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 14,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "radius of largest sphere is 0.1547 r\n",
+      "maximum radius of sphere is 0.414 r\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "from sympy import Symbol\n",
+    "\n",
+    "#Variable declaration\n",
+    "r=Symbol('r')\n",
+    "\n",
+    "#Calculation\n",
+    "a1=4*r/math.sqrt(3);\n",
+    "R1=(a1/2)-r;           #radius of largest sphere\n",
+    "a2=4*r/math.sqrt(2);\n",
+    "R2=(a2/2)-r;       #maximum radius of sphere\n",
+    "\n",
+    "#Result\n",
+    "print \"radius of largest sphere is\",round(R1/r,4),\"r\"\n",
+    "print \"maximum radius of sphere is\",round(R2/r,3),\"r\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 7, Page number 2.25"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 15,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "percent volume change is 0.5 %\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "r1=1.258*10**-10;     #radius(m)\n",
+    "r2=1.292*10**-10;     #radius(m)\n",
+    "\n",
+    "#Calculation\n",
+    "a_bcc=4*r1/math.sqrt(3);\n",
+    "v=a_bcc**3;\n",
+    "V1=v/2;\n",
+    "a_fcc=2*math.sqrt(2)*r2;\n",
+    "V2=a_fcc**3/4;\n",
+    "V=(V1-V2)*100/V1;           #percent volume change is\",V,\"%\"\n",
+    "\n",
+    "#Result\n",
+    "print \"percent volume change is\",round(V,1),\"%\""
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.11"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/Solid_State_Physics_by_Dr_M_Arumugam/Chapter3.ipynb b/Solid_State_Physics_by_Dr_M_Arumugam/Chapter3.ipynb
new file mode 100644
index 00000000..a9d0fcd4
--- /dev/null
+++ b/Solid_State_Physics_by_Dr_M_Arumugam/Chapter3.ipynb
@@ -0,0 +1,303 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# 3: X-Ray Diffraction"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 1, Page number 3.9"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "maximum order of diffraction is 1.53\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "d=1.181;       #lattice spacing(angstrom)\n",
+    "theta=90*math.pi/180;     #glancing angle(radian)\n",
+    "lamda=1.540;    #wavelength of X-rays(angstrom)\n",
+    "\n",
+    "#Calculation\n",
+    "n=2*d*math.sin(theta)/lamda;       #maximum order of diffraction \n",
+    "\n",
+    "#Result\n",
+    "print \"maximum order of diffraction is\",round(n,2)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 2, Page number 3.9"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 4,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "cube edge of unit cell is 3.514 angstrom\n",
+      "answer given in the book varies due to rounding off errors\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "n=1;     #order\n",
+    "theta=9.5*math.pi/180;     #glancing angle(radian)\n",
+    "lamda=0.58;                 #wavelength(angstrom)\n",
+    "h=2;\n",
+    "k=0;\n",
+    "l=0;\n",
+    "\n",
+    "#Calculation\n",
+    "d=n*lamda/(2*math.sin(theta));       #lattice parameter(angstrom)\n",
+    "a=d*math.sqrt(h**2+k**2+l**2);       #cube edge of unit cell(angstrom)\n",
+    "\n",
+    "#Result\n",
+    "print \"cube edge of unit cell is\",round(a,3),\"angstrom\"\n",
+    "print \"answer given in the book varies due to rounding off errors\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 3, Page number 3.10"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 7,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "glancing angle for 3rd order is 26 degrees 35 minutes\n",
+      "answer for minutes given in the book is wrong\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "theta=(8+(35/60))*math.pi/180;     #glancing angle(radian)\n",
+    "lamda=0.842;   #wavelength of X-rays(angstrom)\n",
+    "n1=1;                  #order\n",
+    "n3=3;                  #order \n",
+    "\n",
+    "#Calculation\n",
+    "theta3=math.asin(n3*lamda*math.sin(theta)/(n1*lamda))*180/math.pi;    #glancing angle for 3rd order(degrees)\n",
+    "theta3d=int(theta3);                             #glancing angle for 3rd order(degrees)  \n",
+    "theta3m=(theta3-theta3d)*60;                     #glancing angle for 3rd order(minutes)\n",
+    "\n",
+    "#Result\n",
+    "print \"glancing angle for 3rd order is\",theta3d,\"degrees\",int(theta3m),\"minutes\"\n",
+    "print \"answer for minutes given in the book is wrong\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 4, Page number 3.10"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 11,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "interplanar spacing is 2.22 angstrom\n",
+      "value of h**2+k**2+l**2 is 2\n",
+      "miller indices are (110) or (011) or (101)\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "theta=20.3*math.pi/180;     #glancing angle(radian)\n",
+    "lamda=1.54;   #wavelength of X-rays(angstrom)\n",
+    "n=1;          #order\n",
+    "a=3.16;       #lattice parameter(angstrom)\n",
+    "\n",
+    "#Calculation\n",
+    "d=n*lamda/(2*math.sin(theta));       #interplanar spacing(angstrom)\n",
+    "x=(a/d)**2;        #assume x=(h**2+k**2+l**2)\n",
+    "\n",
+    "#Result\n",
+    "print \"interplanar spacing is\",round(d,2),\"angstrom\"\n",
+    "print \"value of h**2+k**2+l**2 is\",int(x)\n",
+    "print \"miller indices are (110) or (011) or (101)\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 5, Page number 3.11"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 12,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "wavelength is 1.553 angstrom\n",
+      "energy of X-rays is 8 *10**3 eV\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "n=4;     #order\n",
+    "A=107.87;     #atomic weight(kg)\n",
+    "theta=(19+(12/60))*math.pi/180;     #glancing angle(radian)\n",
+    "h=1;\n",
+    "k=1;\n",
+    "l=1;\n",
+    "N=6.02*10**26;          #avagadro number\n",
+    "rho=10500;              #density(kg/m**3)\n",
+    "H=6.625*10**-34;        #plancks constant(Js)\n",
+    "c=3*10**8;              #velocity of light(m/s)\n",
+    "e=1.6*10**-19;          #charge(coulomb)\n",
+    "\n",
+    "#Calculation\n",
+    "a=round(((n*A/(N*rho))**(1/3))*10**10,2);   #lattice parameter(angstrom)\n",
+    "d=a/math.sqrt((h**2)+(k**2)+(l**2));     #lattice parameter(angstrom)\n",
+    "lamda=2*d*math.sin(theta);         #wavelength(angstrom)\n",
+    "E=H*c/(lamda*10**-10*e);                   #energy of X-rays(eV)\n",
+    "\n",
+    "#Result\n",
+    "print \"wavelength is\",round(lamda,3),\"angstrom\"\n",
+    "print \"energy of X-rays is\",int(round(E/10**3)),\"*10**3 eV\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 6, Page number 3.12"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 22,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "specimen distance is 7.559 cm\n",
+      "answer given in the book varies due to rounding off errors\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "h=1;\n",
+    "k=1;\n",
+    "l=1;\n",
+    "a=4.57;   #lattice parameter(angstrom)\n",
+    "lamda=1.52;         #wavelength(angstrom)\n",
+    "r=5;        #radius(cm)\n",
+    "\n",
+    "#Calculation\n",
+    "d=a/math.sqrt(h**2+k**2+l**2);     #lattice parameter(angstrom)\n",
+    "theta=math.asin(lamda/(2*d));      #glancing angle(degrees)\n",
+    "X=r/math.tan(2*theta);             #specimen distance(cm)\n",
+    "\n",
+    "#Result\n",
+    "print \"specimen distance is\",round(X,3),\"cm\"\n",
+    "print \"answer given in the book varies due to rounding off errors\""
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.11"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/Solid_State_Physics_by_Dr_M_Arumugam/Chapter4.ipynb b/Solid_State_Physics_by_Dr_M_Arumugam/Chapter4.ipynb
new file mode 100644
index 00000000..e9783bbb
--- /dev/null
+++ b/Solid_State_Physics_by_Dr_M_Arumugam/Chapter4.ipynb
@@ -0,0 +1,211 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# 4: Defects in Crystals"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 1, Page number 4.14"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 36,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "equilibrium concentration of vacancy at 300K is 7.577 *10**5\n",
+      "equilibrium concentration of vacancy at 900K is 6.502 *10**19\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "N=6.023*10**26;  #avagadro number\n",
+    "T1=1/float('inf');     #temperature 0K(K)\n",
+    "T2=300;\n",
+    "T3=900;         #temperature(K)\n",
+    "k=1.38*10**-23; #boltzmann constant \n",
+    "deltaHv=120*10**3*10**3/N;    #enthalpy(J/vacancy)\n",
+    "\n",
+    "#Calculation\n",
+    "#n1=N*math.exp(-deltaHv/(k*T1));    #equilibrium concentration of vacancy at 0K\n",
+    "#value of n1 cant be calculated in python, as the denominator is 0 and it shows float division error\n",
+    "n2=N*math.exp(-deltaHv/(k*T2));    #equilibrium concentration of vacancy at 300K \n",
+    "n3=N*math.exp(-deltaHv/(k*T3));    #equilibrium concentration of vacancy at 900K \n",
+    "\n",
+    "#Result\n",
+    "#print \"equilibrium concentration of vacancy at 0K is\",n1\n",
+    "print \"equilibrium concentration of vacancy at 300K is\",round(n2/10**5,3),\"*10**5\"\n",
+    "print \"equilibrium concentration of vacancy at 900K is\",round(n3/10**19,3),\"*10**19\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 2, Page number 4.15"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "fraction of vacancies at 1000 is 8.5 *10**-7\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "nbyN1=1*10**-10;      #fraction of vacancies\n",
+    "T1=500+273;\n",
+    "T2=1000+273;\n",
+    "\n",
+    "#Calculation\n",
+    "lnx=T1*math.log(nbyN1)/T2;\n",
+    "x=math.exp(lnx);      #fraction of vacancies at 1000\n",
+    "\n",
+    "#Result\n",
+    "print \"fraction of vacancies at 1000 is\",round(x*10**7,1),\"*10**-7\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 3, Page number 4.16"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 5,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "concentration of schottky defects is 6.42 *10**11 per m**3\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "d=2.82*10**-10;    #interionic distance(m)\n",
+    "T=300;             #temperature(K)\n",
+    "k=1.38*10**-23;    #boltzmann constant \n",
+    "e=1.6*10**-19;     #charge(coulomb)\n",
+    "n=4;               #number of molecules\n",
+    "deltaHs=1.971*e;   #enthalpy(J)\n",
+    "\n",
+    "#Calculation\n",
+    "V=(2*d)**3;        #volume of unit cell(m**3)\n",
+    "N=n/V;             #number of ion pairs\n",
+    "x=deltaHs/(2*k*T);\n",
+    "n=N*math.exp(-x);    #concentration of schottky defects(per m**3)\n",
+    "\n",
+    "#Result\n",
+    "print \"concentration of schottky defects is\",round(n*10**-11,2),\"*10**11 per m**3\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 4, Page number 4.17"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 16,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "concentration of schottky defects is 9.23 *10**12 per cm**3\n",
+      "amount of climb down by the dislocations is 0.1846 step or 0.3692 *10**-8 cm\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "N=6.026*10**23;    #avagadro number \n",
+    "T=500;             #temperature(K)\n",
+    "k=1.38*10**-23;    #boltzmann constant \n",
+    "deltaHv=1.6*10**-19;     #charge(coulomb)\n",
+    "V=5.55;            #molar volume(cm**3)\n",
+    "nv=5*10**7*10**6;  #number of vacancies\n",
+    "\n",
+    "#Calculation\n",
+    "n=N*math.exp(-deltaHv/(k*T))/V;    #concentration of schottky defects(per m**3)\n",
+    "x=round(n/nv,4);            #amount of climb down by the dislocations(step)\n",
+    "xcm=2*x*10**-8;             #amount of climb down by the dislocations(cm)\n",
+    "\n",
+    "#Result\n",
+    "print \"concentration of schottky defects is\",round(n/10**12,2),\"*10**12 per cm**3\"\n",
+    "print \"amount of climb down by the dislocations is\",x,\"step or\",xcm*10**8,\"*10**-8 cm\" "
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.11"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/Solid_State_Physics_by_Dr_M_Arumugam/Chapter5.ipynb b/Solid_State_Physics_by_Dr_M_Arumugam/Chapter5.ipynb
new file mode 100644
index 00000000..be92b558
--- /dev/null
+++ b/Solid_State_Physics_by_Dr_M_Arumugam/Chapter5.ipynb
@@ -0,0 +1,121 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# 5: Elements of Statistical Mechanics"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 3, Page number 5.32"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "temperature is 1261.6 K\n",
+      "answer given in the book is wrong\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "E=5.5;          #energy(eV)\n",
+    "Ef=5;           #fermi energy(eV)\n",
+    "p=1/100;        #probability\n",
+    "e=1.6*10**-19;  #charge(coulomb)\n",
+    "k=1.38*10**-23; #boltzmann constant \n",
+    "\n",
+    "#Calculation\n",
+    "x=E-Ef;         #difference in energy(eV)\n",
+    "y=math.log((1/p)-1);\n",
+    "T=x*e/(k*y);    #temperature(K)\n",
+    "\n",
+    "#Result\n",
+    "print \"temperature is\",round(T,1),\"K\"\n",
+    "print \"answer given in the book is wrong\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 4, Page number 5.32"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 4,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "fermi energy is 3.15 eV\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "rho=970;        #density(kg/m**3)\n",
+    "N=6.02*10**26;  #avagadro number\n",
+    "A=23;           #atomic weight(kg)\n",
+    "h=6.62*10**-34; #planks constant(Js)\n",
+    "m=9.1*10**-31;  #mass(kg)\n",
+    "e=1.6*10**-19;  #charge(coulomb)\n",
+    "\n",
+    "#Calculation\n",
+    "n=rho*N/A;      #number of atoms per m**3\n",
+    "EF=(h**2/(8*m))*((3*n/math.pi)**(2/3));     #fermi energy(J)\n",
+    "EF=EF/e;        #fermi energy(eV)\n",
+    "\n",
+    "#Result\n",
+    "print \"fermi energy is\",round(EF,2),\"eV\""
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.11"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/Solid_State_Physics_by_Dr_M_Arumugam/Chapter6.ipynb b/Solid_State_Physics_by_Dr_M_Arumugam/Chapter6.ipynb
new file mode 100644
index 00000000..ab8cdc23
--- /dev/null
+++ b/Solid_State_Physics_by_Dr_M_Arumugam/Chapter6.ipynb
@@ -0,0 +1,331 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# 6: Principles of Quantum Mechanics"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 1, Page number 6.22"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "deBroglie wavelength is 0.66 angstrom\n",
+      "spacing between planes is 0.35 angstrom\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "V=344;         #voltage(V)\n",
+    "theta=40;      #angle(degrees)\n",
+    "n=1; \n",
+    "\n",
+    "#Calculation\n",
+    "lamda=12.26/math.sqrt(V);    #deBroglie wavelength(angstrom)\n",
+    "theta=((180-theta)/2)*math.pi/180;    #angle(radian)\n",
+    "d=n*lamda/(2*math.sin(theta));        #spacing between planes(angstrom)\n",
+    "\n",
+    "#Result\n",
+    "print \"deBroglie wavelength is\",round(lamda,2),\"angstrom\"\n",
+    "print \"spacing between planes is\",round(d,2),\"angstrom\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 2, Page number 6.22"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 6,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "deBroglie wavelength is 0.00286 angstrom\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "e=1.6*10**-19;       #charge(coulomb)\n",
+    "m=1.675*10**-27;     #mass(kg)\n",
+    "E=10*10**3*e;        #kinetic energy(J)\n",
+    "h=6.625*10**-34;     #planks constant(Js)\n",
+    "\n",
+    "#Calculation\n",
+    "v=math.sqrt(2*E/m);    #velocity(m/sec)\n",
+    "lamda=h*10**10/(m*v);  #deBroglie wavelength(angstrom)\n",
+    "\n",
+    "#Result\n",
+    "print \"deBroglie wavelength is\",round(lamda,5),\"angstrom\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 3, Page number 6.22"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 8,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "energy difference is 1.81 *10**-37 J\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "m=9.1*10**-31;     #mass(kg)\n",
+    "h=6.63*10**-34;    #planks constant(Js)\n",
+    "a=1;               #length(m)\n",
+    "nx1=1;\n",
+    "ny1=1;\n",
+    "nz1=1;\n",
+    "nx2=1;\n",
+    "ny2=1;\n",
+    "nz2=2;\n",
+    "\n",
+    "#Calculation\n",
+    "E1=h**2*(nx1**2+ny1**2+nz1**2)/(8*m*a**2);     #energy of 1st quantum state(J)\n",
+    "E2=h**2*(nx2**2+ny2**2+nz2**2)/(8*m*a**2);     #energy of 2nd quantum state(J)\n",
+    "E=E2-E1;          #energy difference(J)\n",
+    "\n",
+    "#Result\n",
+    "print \"energy difference is\",round(E*10**37,2),\"*10**-37 J\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 4, Page number 6.23"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 12,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "uncertainity in position of electron is 0.002 m\n",
+      "uncertainity in position of bullet is 0.4 *10**-31 m\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "m1=9.1*10**-31;     #mass(kg)\n",
+    "m2=0.05;            #mass(kg)\n",
+    "v=300;              #velocity(m/sec)\n",
+    "p=0.01/100;         #probability\n",
+    "h=6.6*10**-34;      #planks constant(Js)\n",
+    "\n",
+    "#Calculation\n",
+    "p1=m1*v;            #momentum of electron(kg m/s)\n",
+    "deltap1=p*p1;      \n",
+    "deltax1=h/(deltap1*4*math.pi);   #uncertainity in position of electron(m)\n",
+    "p2=m2*v;            #momentum of bullet(kg m/s)\n",
+    "deltap2=p*p2;      \n",
+    "deltax2=h/(deltap2*4*math.pi);   #uncertainity in position of bullet(m)\n",
+    "\n",
+    "#Result\n",
+    "print \"uncertainity in position of electron is\",round(deltax1,3),\"m\"\n",
+    "print \"uncertainity in position of bullet is\",round(deltax2*10**31,1),\"*10**-31 m\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 5, Page number 6.24"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 13,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "probability of finding the particle is 0.2\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "deltax=10**-10;     #uncertainity in position(m)\n",
+    "L=10*10**-10;       #width(m)\n",
+    "\n",
+    "#Calculation\n",
+    "p=2*deltax/L;       #probability of finding the particle\n",
+    "\n",
+    "#Result\n",
+    "print \"probability of finding the particle is\",p"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 6, Page number 6.24"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 15,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "deBroglie wavelength is 2.73 *10**-11 m\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "e=1.6*10**-19;       #charge(coulomb)\n",
+    "m=9.1*10**-31;       #mass(kg)\n",
+    "E=2*10**3*e;         #kinetic energy(J)\n",
+    "h=6.6*10**-34;       #planks constant(Js)\n",
+    "\n",
+    "#Calculation\n",
+    "p=math.sqrt(2*E*m);    #momentum(kg m/s)\n",
+    "lamda=h/p;             #deBroglie wavelength(m)\n",
+    "\n",
+    "#Result\n",
+    "print \"deBroglie wavelength is\",round(lamda*10**11,2),\"*10**-11 m\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 7, Page number 6.24"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 21,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "deBroglie wavelength is 1.807 angstrom\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "e=1.602*10**-19;       #charge(coulomb)\n",
+    "m=1.676*10**-27;       #mass(kg)\n",
+    "h=6.62*10**-34;        #planks constant(Js)\n",
+    "E=0.025*e;             #kinetic energy(J)\n",
+    "\n",
+    "#Calculation\n",
+    "mv=math.sqrt(2*E*m);    #velocity(m/s)\n",
+    "lamda=h*10**10/mv;      #deBroglie wavelength(angstrom)\n",
+    "\n",
+    "#Result\n",
+    "print \"deBroglie wavelength is\",round(lamda,3),\"angstrom\""
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.11"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
diff --git a/Solid_State_Physics_by_Dr_M_Arumugam/Chapter8.ipynb b/Solid_State_Physics_by_Dr_M_Arumugam/Chapter8.ipynb
new file mode 100644
index 00000000..8d27e900
--- /dev/null
+++ b/Solid_State_Physics_by_Dr_M_Arumugam/Chapter8.ipynb
@@ -0,0 +1,280 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# 8: Semiconductor Physics"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 1, Page number 8.19"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "number of electron hole pairs is 2.32 *10**16 per cubic metre\n",
+      "answer varies due to rounding off errors\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "ni1=2.5*10**19;    #number of electron hole pairs\n",
+    "T1=300;     #temperature(K)\n",
+    "Eg1=0.72*1.6*10**-19;    #energy gap(J)\n",
+    "k=1.38*10**-23;     #boltzmann constant\n",
+    "T2=310;    #temperature(K)\n",
+    "Eg2=1.12*1.6*10**-19;    #energy gap(J)\n",
+    "\n",
+    "#Calculation\n",
+    "x1=-Eg1/(2*k*T1);\n",
+    "y1=(T1**(3/2))*math.exp(x1);\n",
+    "x2=-Eg2/(2*k*T2);\n",
+    "y2=(T2**(3/2))*math.exp(x2);\n",
+    "ni=ni1*(y2/y1);          #number of electron hole pairs\n",
+    "\n",
+    "#Result\n",
+    "print \"number of electron hole pairs is\",round(ni/10**16,2),\"*10**16 per cubic metre\"\n",
+    "print \"answer varies due to rounding off errors\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 2, Page number 8.20"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 13,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "intrinsic conductivity is 2.016 ohm-1 metre-1\n",
+      "intrinsic resistivity is 0.496 ohm metre\n",
+      "number of germanium atoms per m**3 is 4.5 *10**28\n",
+      "new value of conductivity is 1.434 *10**4 ohm-1 metre-1\n",
+      "new value of resistivity is 0.697 *10**-4 ohm metre\n",
+      "answer for new values given in the book varies due to rounding off errors\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "w=72.6;    #atomic weight\n",
+    "d=5400;    #density(kg/m**3)\n",
+    "Na=6.025*10**26;    #avagadro number\n",
+    "mew_e=0.4;    #mobility of electron(m**2/Vs)\n",
+    "mew_h=0.2;    #mobility of holes(m**2/Vs)\n",
+    "e=1.6*10**-19;\n",
+    "m=9.108*10**-31;    #mass(kg)\n",
+    "ni=2.1*10**19;      #number of electron hole pairs\n",
+    "Eg=0.7;    #band gap(eV)\n",
+    "k=1.38*10**-23;    #boltzmann constant\n",
+    "h=6.625*10**-34;    #plancks constant\n",
+    "T=300;     #temperature(K)\n",
+    "\n",
+    "#Calculation\n",
+    "sigma=ni*e*(mew_e+mew_h);    #intrinsic conductivity(ohm-1 m-1)\n",
+    "rho=1/sigma;     #resistivity(ohm m)\n",
+    "n=Na*d/w;        #number of germanium atoms per m**3\n",
+    "p=n/10**5;       #boron density\n",
+    "sigman=p*e*mew_h;  #new value of conductivity(ohm-1 metre-1)\n",
+    "rhon=1/sigman;     #new value of resistivity(ohm metre)\n",
+    "\n",
+    "#Result\n",
+    "print \"intrinsic conductivity is\",sigma,\"ohm-1 metre-1\"\n",
+    "print \"intrinsic resistivity is\",round(rho,3),\"ohm metre\"\n",
+    "print \"number of germanium atoms per m**3 is\",round(n/10**28,1),\"*10**28\"\n",
+    "print \"new value of conductivity is\",round(sigman/10**4,3),\"*10**4 ohm-1 metre-1\"\n",
+    "print \"new value of resistivity is\",round(rhon*10**4,3),\"*10**-4 ohm metre\"\n",
+    "print \"answer for new values given in the book varies due to rounding off errors\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 3, Page number 8.21"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 14,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "charge carrier density is 2 *10**22 per m**3\n",
+      "electron mobility is 0.035 m**2/Vs\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "e=1.6*10**-19;\n",
+    "RH=3.66*10**-4;    #hall coefficient(m**3/coulomb)\n",
+    "sigma=112;      #conductivity(ohm-1 m-1)\n",
+    "\n",
+    "#Calculation\n",
+    "ne=3*math.pi/(8*RH*e);    #charge carrier density(per m**3)\n",
+    "mew_e=sigma/(e*ne);      #electron mobility(m**2/Vs)\n",
+    "\n",
+    "#Result\n",
+    "print \"charge carrier density is\",int(ne/10**22),\"*10**22 per m**3\"\n",
+    "print \"electron mobility is\",round(mew_e,3),\"m**2/Vs\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 4, Page number 8.21"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 16,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "intrinsic conductivity is 0.432 *10**-3 ohm-1 m-1\n",
+      "conductivity during donor impurity is 10.4 ohm-1 m-1\n",
+      "conductivity during acceptor impurity is 4 ohm-1 m-1\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "mew_e=0.13;    #mobility of electron(m**2/Vs)\n",
+    "mew_h=0.05;    #mobility of holes(m**2/Vs)\n",
+    "e=1.6*10**-19;\n",
+    "ni=1.5*10**16;      #number of electron hole pairs\n",
+    "N=5*10**28;\n",
+    "\n",
+    "#Calculation\n",
+    "sigma1=ni*e*(mew_e+mew_h);    #intrinsic conductivity(ohm-1 m-1)\n",
+    "ND=N/10**8;\n",
+    "n=ni**2/ND;\n",
+    "sigma2=ND*e*mew_e;     #conductivity(ohm-1 m-1)\n",
+    "sigma3=ND*e*mew_h;     #conductivity(ohm-1 m-1)\n",
+    "\n",
+    "#Result\n",
+    "print \"intrinsic conductivity is\",round(sigma1*10**3,3),\"*10**-3 ohm-1 m-1\"\n",
+    "print \"conductivity during donor impurity is\",sigma2,\"ohm-1 m-1\"\n",
+    "print \"conductivity during acceptor impurity is\",int(sigma3),\"ohm-1 m-1\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Example number 5, Page number 8.22"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 18,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "conductivity is 4.97 mho m-1\n"
+     ]
+    }
+   ],
+   "source": [
+    "#importing modules\n",
+    "import math\n",
+    "from __future__ import division\n",
+    "\n",
+    "#Variable declaration\n",
+    "e=1.6*10**-19;\n",
+    "Eg=0.72;    #band gap(eV)\n",
+    "k=1.38*10**-23;    #boltzmann constant\n",
+    "T1=293;     #temperature(K)\n",
+    "T2=313;     #temperature(K)\n",
+    "sigma1=2;    #conductivity(mho m-1)\n",
+    "\n",
+    "#Calculation\n",
+    "x=(Eg*e/(2*k))*((1/T1)-(1/T2));\n",
+    "y=round(x/2.303,3);\n",
+    "z=round(math.log10(sigma1),3);\n",
+    "log_sigma2=y+z;\n",
+    "sigma2=10**log_sigma2;     #conductivity(mho m-1)\n",
+    "\n",
+    "#Result\n",
+    "print \"conductivity is\",round(sigma2,2),\"mho m-1\""
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 2",
+   "language": "python",
+   "name": "python2"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 2
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython2",
+   "version": "2.7.11"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
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