adding books

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diff --git a/Solid_state_physics/Chapter_1.ipynb b/Solid_state_physics/Chapter_1.ipynb
new file mode 100755
index 00000000..32644890
--- /dev/null
+++ b/Solid_state_physics/Chapter_1.ipynb
@@ -0,0 +1,200 @@
+{
+ "metadata": {
+  "name": ""
+ },
+ "nbformat": 3,
+ "nbformat_minor": 0,
+ "worksheets": [
+  {
+   "cells": [
+    {
+     "cell_type": "heading",
+     "level": 1,
+     "metadata": {},
+     "source": [
+      "Chapter 1: Bonding in Solids"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 1.1, Page number 1.4"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "from math import pi\n",
+      "\n",
+      "#Variable declartion\n",
+      "E_a = 502        #first ionization energy of A(kJ/mol)\n",
+      "E_b = -335       #electron affinity for B atom(kJ/mol)\n",
+      "d = 3*10**-10    #inter-ionic seperation(m)\n",
+      "E = 8.85*10**-12 #permittivity of free space(C/N -m)\n",
+      "e = 1.602*10**-19#charge of an electron(C)\n",
+      "\n",
+      "#Calculations\n",
+      "C_e = (-e**2)/(4*pi*E*d)           #Coulumbic attraction energy(J/ion pair)\n",
+      "C_e_kj = C_e *6.022*10**23*10**-3  #Converting C_e to KJ/mol\n",
+      "n_e = E_a + E_b  + C_e_kj          #Net change in energy per mole\n",
+      "\n",
+      "#Results\n",
+      "print \"Net change in energy is =\",round(n_e,3),\"kJ/mol\"\n",
+      "print \"As the net change in energy is negative, the molecule will be stable\"\n",
+      "print \"\\nThe solution differs because of rounding-off of the digits in the textbook\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Net change in energy is = -296.224 kJ/mol\n",
+        "As the net change in energy is negative, the molecule will be stable\n",
+        "\n",
+        "The solution differs because of rounding-off of the digits in the textbook\n"
+       ]
+      }
+     ],
+     "prompt_number": 19
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 1.2, Page number 1.4"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "from math import pi \n",
+      "\n",
+      "#Variable declaration\n",
+      "IP_K = 4.1        #ionization energy of K(eV)\n",
+      "EA_Cl = 3.6       #electron affinity of Cl(eV)\n",
+      "e = 1.602*10**-19 #charge of an electron(C)\n",
+      "Eo = 8.85*10**-12 #permittivity of free space(C/N -m)\n",
+      "\n",
+      "#Calcuations\n",
+      "del_E = IP_K - EA_Cl\n",
+      "#Ec = 0.5 = -e/4*pi*Eo*R\n",
+      "R = e/(4*pi*Eo*del_E)\n",
+      "\n",
+      "#Results\n",
+      "print \"(a) If their total energy is to be zero, then del_E = Ec\"\n",
+      "print \"(b) The seperation between the ion pair is\", round((R/1E-9),2), \"nm\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "(a) If their total energy is to be zero, then del_E = Ec\n",
+        "(b) The seperation between the ion pair is 2.88 nm\n"
+       ]
+      }
+     ],
+     "prompt_number": 7
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 1.3, Page number 1.5"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "from math import pi\n",
+      "\n",
+      "#Variable declaration\n",
+      "ro = 2.36*10**-10  #inter ionic equilibrium distance(m)\n",
+      "IP = 5.14          #ionization energy of Na(eV)\n",
+      "EA = 3.65          #electron affinity of Cl(eV)\n",
+      "e = 1.602*10**-19  #charge of an electron(C)\n",
+      "Eo = 8.85*10**-12  #permittivity of free space(C/N -m)\n",
+      "\n",
+      "#Calculations\n",
+      "Ue = (-e**2)/(4*pi*Eo*ro*e) #Potential energy in eV\n",
+      "Be = -Ue - IP + EA\n",
+      "\n",
+      "#Result\n",
+      "print \"Bond energy for NaCl molecule is\",round(Be,2),\"eV\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Bond energy for NaCl molecule is 4.61 eV\n"
+       ]
+      }
+     ],
+     "prompt_number": 9
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 1.4, Page number 1.18"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "from math import pi\n",
+      "\n",
+      "#Variable declaration\n",
+      "ro = 0.281*10**-9 #equilibrium seperation between the ion pair(m)\n",
+      "IP = 5.14         #ionization energy of Na(eV)\n",
+      "EA = 3.61         #electron affinity of Cl(eV)\n",
+      "A = 1.748         #Madelung constant\n",
+      "n = 9.            #born replusive exponent\n",
+      "e = 1.602*10**-19 #charge of an electron(C)\n",
+      "Eo = 8.85*10**-12 #permittivity of free space(C/N -m)\n",
+      "\n",
+      "#Calculations\n",
+      "Ce = (A*(e**2)*(1-(1/n)))/(4*pi*Eo*ro) #joules\n",
+      "Ce_ev = Ce/e                           #Converting joules to eV\n",
+      "\n",
+      "#Result\n",
+      "print \"The cohesive energy of NaCl molecule is\",round(Ce_ev,2),\"eV\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The cohesive energy of NaCl molecule is 7.97 eV\n"
+       ]
+      }
+     ],
+     "prompt_number": 22
+    }
+   ],
+   "metadata": {}
+  }
+ ]
+}
\ No newline at end of file
diff --git a/Solid_state_physics/Chapter_10.ipynb b/Solid_state_physics/Chapter_10.ipynb
new file mode 100755
index 00000000..ac36fbe7
--- /dev/null
+++ b/Solid_state_physics/Chapter_10.ipynb
@@ -0,0 +1,181 @@
+{
+ "metadata": {
+  "name": ""
+ },
+ "nbformat": 3,
+ "nbformat_minor": 0,
+ "worksheets": [
+  {
+   "cells": [
+    {
+     "cell_type": "heading",
+     "level": 1,
+     "metadata": {},
+     "source": [
+      "Chapter 10: Superconductivity"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 10.1, Page number 10.3"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "Tc = 3.7       #critical temperature(K)\n",
+      "Hc_o = 0.0306  #critical field(T)\n",
+      "T = 2          #temperature(K)\n",
+      "\n",
+      "#Calculation\n",
+      "Hc_2 = Hc_o*(1-((T/Tc)**2))\n",
+      "\n",
+      "#Result\n",
+      "print \"Critical field at 2K is\",round(Hc_2,5),\"T\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Critical field at 2K is 0.02166 T\n"
+       ]
+      }
+     ],
+     "prompt_number": 1
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 10.2, Page number 10.5"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "from math import pi\n",
+      "\n",
+      "#Variable declaration\n",
+      "T = 4.2        #temperature(K)\n",
+      "Tc = 7.18      #critical temperature(K)\n",
+      "Ho = 6.5*10**4 #A/m\n",
+      "d = 1*10**-3   #diameter(m)\n",
+      "\n",
+      "#Calculations\n",
+      "Hc = Ho*(1-((T/Tc)**2))\n",
+      "r = d/2\n",
+      "ic = 2*pi*r*Hc\n",
+      "\n",
+      "#Result\n",
+      "print \"Critical current =\",round(ic,2),\"A\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Critical current = 134.33 A\n"
+       ]
+      }
+     ],
+     "prompt_number": 2
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 10.3, Page number 10.12"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "import math \n",
+      "\n",
+      "#Variable declaration\n",
+      "T = 3.5         #temperature(K)\n",
+      "lamda_t = 750   #penetration depth at T(A)\n",
+      "Tc = 4.12       #K\n",
+      "\n",
+      "#Calculation\n",
+      "lamda_o = lamda_t*math.sqrt((1-((T/Tc)**4)))\n",
+      "\n",
+      "#Result\n",
+      "print \"Penetration depth at 4.12K is\",round(lamda_o,1),\"A\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Penetration depth at 4.12K is 519.2 A\n"
+       ]
+      }
+     ],
+     "prompt_number": 7
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 10.4, Page number 10.13"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "T1 = 3          #temperature(K)\n",
+      "lamda_t1 = 396.  #penetration depth at T1(A)\n",
+      "T2 = 7.1        #temperature(K)\n",
+      "lamda_t2 = 1730. #penetration depth at T2(A)\n",
+      "\n",
+      "#Calculations\n",
+      "x = lamda_t2**2/lamda_t1**2\n",
+      "Tc = math.sqrt(math.sqrt((-T1**4+(x*(T2**4)))/(x-1)))\n",
+      "\n",
+      "#Result\n",
+      "print \"Critical temperature =\",round(Tc,3),\"K\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Critical temperature = 7.193 K\n"
+       ]
+      }
+     ],
+     "prompt_number": 18
+    }
+   ],
+   "metadata": {}
+  }
+ ]
+}
\ No newline at end of file
diff --git a/Solid_state_physics/Chapter_11.ipynb b/Solid_state_physics/Chapter_11.ipynb
new file mode 100755
index 00000000..2ccb0979
--- /dev/null
+++ b/Solid_state_physics/Chapter_11.ipynb
@@ -0,0 +1,102 @@
+{
+ "metadata": {
+  "name": ""
+ },
+ "nbformat": 3,
+ "nbformat_minor": 0,
+ "worksheets": [
+  {
+   "cells": [
+    {
+     "cell_type": "heading",
+     "level": 1,
+     "metadata": {},
+     "source": [
+      "Chapter 11:Lasers"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 11.1, Page number 11.6"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "lamda = 6943.*10**-10  #wavelength(m)\n",
+      "T = 300.               #temperature(K)\n",
+      "h = 6.626*10**-34      #Planck's constant\n",
+      "c = 3*10**8            #velocity of light(m/s)\n",
+      "K = 8.61*10**-5\n",
+      "\n",
+      "#Calculations\n",
+      "E2_E1 = (h*c)/(lamda*1.6*10**-19) #in eV\n",
+      "N2_N1 = math.exp(-E2_E1/(K*T))\n",
+      "\n",
+      "#Result\n",
+      "print \"The relative population of two states in a ruby laser is\",round((N2_N1/1E-31),2)"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The relative population of two states in a ruby laser is 8.2\n"
+       ]
+      }
+     ],
+     "prompt_number": 12
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 11.2, Page number 11.14"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "a1 = 4.   #diameter of laser beam for distance first(m)\n",
+      "a2 = 6.   # diameter of laser beam from second distance(m)\n",
+      "d1 = 1.   #First distance from laser to output beam spot(m)\n",
+      "d2 = 2.   #Second distance from laser to output beam spot(m)\n",
+      "\n",
+      "#Calculation\n",
+      "D = (a2-a1)/(2*(d2-d1))\n",
+      "\n",
+      "#Result\n",
+      "print \"Divergence =\",D,\"milliradian\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Divergence = 1.0 milliradian\n"
+       ]
+      }
+     ],
+     "prompt_number": 14
+    }
+   ],
+   "metadata": {}
+  }
+ ]
+}
\ No newline at end of file
diff --git a/Solid_state_physics/Chapter_12.ipynb b/Solid_state_physics/Chapter_12.ipynb
new file mode 100755
index 00000000..2311a687
--- /dev/null
+++ b/Solid_state_physics/Chapter_12.ipynb
@@ -0,0 +1,252 @@
+{
+ "metadata": {
+  "name": ""
+ },
+ "nbformat": 3,
+ "nbformat_minor": 0,
+ "worksheets": [
+  {
+   "cells": [
+    {
+     "cell_type": "heading",
+     "level": 1,
+     "metadata": {},
+     "source": [
+      "Chapter 12: Fiber Optics"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 12.1, Page number 12.6"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "n1 = 1.55  #refractive inde of core\n",
+      "n2 = 1.50  #refractive index of cladding\n",
+      "\n",
+      "#Calculation\n",
+      "NA = math.sqrt(n1**2-n2**2)\n",
+      "\n",
+      "#Result\n",
+      "print \"Numerical Aperture =\",round(NA,3)"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Numerical Aperture = 0.391\n"
+       ]
+      }
+     ],
+     "prompt_number": 3
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 12.2, Page number 12.6"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "n1 = 1.563  #refractive inde of core\n",
+      "n2 = 1.498  #refractive index of cladding\n",
+      "\n",
+      "#Calculation\n",
+      "NA = math.sqrt(n1**2-n2**2)\n",
+      "alpha_i = math.degrees(math.asin(NA))\n",
+      "\n",
+      "#Result\n",
+      "print \"Angle of acceptance =\",round(alpha_i,2),\"degrees\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Angle of acceptance = 26.49 degrees\n"
+       ]
+      }
+     ],
+     "prompt_number": 14
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 12.3, Page number 12.6"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "NA = 0.39       #numerical aperture\n",
+      "delta_n = 0.05  #differnce between refractive indices of core & cladding\n",
+      "\n",
+      "#Calculaations\n",
+      "n1 = NA/math.sqrt(2*delta_n)\n",
+      "\n",
+      "#Result\n",
+      "print \"Refractive index of core =\",round(n1,4)"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Refractive index of core = 1.2333\n"
+       ]
+      }
+     ],
+     "prompt_number": 16
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 12.4, Page number 12.7"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "n1 = 1.563  #refractive inde of core\n",
+      "n2 = 1.498  #refractive index of cladding\n",
+      "\n",
+      "#Calculation\n",
+      "delta = (n1-n2)/n1\n",
+      "\n",
+      "#Result\n",
+      "print \"Fractional index change for the given fiber is\",round(delta,4)"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Fractional index change for the given fiber is 0.0416\n"
+       ]
+      }
+     ],
+     "prompt_number": 17
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 12.5, Page number 12.7"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "n1 = 1.48  #refractive inde of core\n",
+      "n2 = 1.45  #refractive index of cladding\n",
+      "\n",
+      "#Calculations\n",
+      "NA = math.sqrt(n1**2-n2**2)\n",
+      "alpha_i = math.degrees(math.asin(NA))\n",
+      "\n",
+      "#Result\n",
+      "print \"Numerical aperture =\",round(NA,4)\n",
+      "print \"Angle of acceptance =\",round(alpha_i,2),\"degrees\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Numerical aperture = 0.2965\n",
+        "Angle of acceptance = 17.25 degrees\n"
+       ]
+      }
+     ],
+     "prompt_number": 18
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 12.6, Page number 12.14"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "Pout = 40.     #output power(mW)\n",
+      "Pin = 100.     #input power(mW)\n",
+      "\n",
+      "#Calculation\n",
+      "A = -10*math.log10(Pout/Pin)  #Attenuation(dB)\n",
+      "\n",
+      "#Result \n",
+      "print \"Attenuation =\",round(A,2),\"dB\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Attenuation = 3.98 dB\n"
+       ]
+      }
+     ],
+     "prompt_number": 22
+    }
+   ],
+   "metadata": {}
+  }
+ ]
+}
\ No newline at end of file
diff --git a/Solid_state_physics/Chapter_2.ipynb b/Solid_state_physics/Chapter_2.ipynb
new file mode 100755
index 00000000..99284878
--- /dev/null
+++ b/Solid_state_physics/Chapter_2.ipynb
@@ -0,0 +1,331 @@
+{
+ "metadata": {
+  "name": "",
+  "signature": "sha256:64e1fbee0e1d9b8157cae12a98a7773b847a3c5e842a9d3f124a5485fe931875"
+ },
+ "nbformat": 3,
+ "nbformat_minor": 0,
+ "worksheets": [
+  {
+   "cells": [
+    {
+     "cell_type": "heading",
+     "level": 1,
+     "metadata": {},
+     "source": [
+      "Chapter 2: Crystal Structure"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 2.1, Page number 2.16"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "from math import sqrt \n",
+      "\n",
+      "#Variable declaration\n",
+      "#Assuming r=1 for simpliciy in calculations\n",
+      "r = 1\n",
+      "\n",
+      "#Calculations\n",
+      "a = (4*r)/sqrt(3)\n",
+      "#Let R be the radius of interstitial sphere that can fit into the void,therefore,\n",
+      "R = (a-2*r)/2     \n",
+      "\n",
+      "#Result\n",
+      "print \"The maximum radius of interstitial sphere is\",round(R,3),\"r\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The maximum radius of interstitial sphere is 0.155 r\n"
+       ]
+      }
+     ],
+     "prompt_number": 2
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 2.2, Page number 2.17"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "from math import sqrt\n",
+      "\n",
+      "#Variable declaration\n",
+      "r1 = 1.258*10**-10   #atomic radius(m)\n",
+      "r2 = 1.292*10**-10   #atomic radius(m)\n",
+      "\n",
+      "#Calculations\n",
+      "#In BCC\n",
+      "a_bcc = (4*r1)/sqrt(3)\n",
+      "v_bcc = a_bcc**3          #volume of unit cell(m^3)\n",
+      "n1 = ((1./8.)*8.)+1\n",
+      "V1 = v_bcc/n1             #volume occupied by 1 atom(m^3)\n",
+      "\n",
+      "#In FCC\n",
+      "a_fcc = 2*sqrt(2)*r2\n",
+      "v_fcc = a_fcc**3          #volume of unit cell(m^3)\n",
+      "n2 = ((1./2.)*6.)+((1./8.)*8.)\n",
+      "V2 = v_fcc/n2             #volume occupied by 1 atom(m^3)\n",
+      "\n",
+      "del_v = ((V1-V2)/V1)*100  #change in volume\n",
+      "\n",
+      "#Result\n",
+      "print \"During the conversion of iron from BCC to FCC, the decrease in volume is\",round(del_v,1),\"%\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "During the conversion of iron from BCC to FCC, the decrease in volume is 0.5 %\n"
+       ]
+      }
+     ],
+     "prompt_number": 3
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 2.3, Page number 2.17"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "from math import sqrt\n",
+      "\n",
+      "#Variable declaration\n",
+      "a = 0.27*10**-9   #nearest neighbour distance(m)\n",
+      "c = 0.494*10**-9  #height of unit cell(m)\n",
+      "M = 65.37         #atomic weight of zinc\n",
+      "N = 6.023*10**26  #Avogadro's number(k/mol)\n",
+      "\n",
+      "#Calculations\n",
+      "V = (3*sqrt(3)*a**2*c)/2  #volume of unit cell\n",
+      "rho = (6*M)/(N*V)         #density of crystal\n",
+      "\n",
+      "#Results\n",
+      "print \"Volume of unit cell =\",round((V/1E-29),2),\"*10^29 m^3\"\n",
+      "print \"Density of zinc =\",round(rho),\"kg/m^3\"\n",
+      "print \"\\nThe solution differs because of rounding-off of the digits in the textbook\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Volume of unit cell = 9.36 *10^29 m^3\n",
+        "Density of zinc = 6960.0 kg/m^3\n",
+        "\n",
+        "The solution differs because of rounding-off of the digits in the textbook\n"
+       ]
+      }
+     ],
+     "prompt_number": 4
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 2.4, Page number 2.18"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "from math import sqrt\n",
+      "\n",
+      "#Varaible declaration\n",
+      "#Let r be the radius of atom and R be the radius of sphere\n",
+      "#For simplicity in calculations, let us assume r =1\n",
+      "r = 1\n",
+      "\n",
+      "#Calculations\n",
+      "#For FCC structure\n",
+      "a = (4*r)/sqrt(2)\n",
+      "R = (a/2)-r\n",
+      "\n",
+      "print \"Maximum radius of sphere =\",round(R,3),\"r\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Maximum radius of sphere = 0.414 r\n"
+       ]
+      }
+     ],
+     "prompt_number": 5
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 2.5, Page number 2.19"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "a = 0.356*10**-9  #cube edge(m)\n",
+      "M = 12.01         #atomic weight of carbon\n",
+      "N = 6.023*10**26  #Avogadro's number(k/mol)\n",
+      "na = 1.77*10**29  #no. of atoms per meter cube\n",
+      "\n",
+      "#Calculations\n",
+      "#Diamond has 2 interpenetrating FCC lattices. Since each FCC unit cell has 4 atoms, the total no. of atoms per unit cell is 8\n",
+      "n = 8/a**3\n",
+      "m = M/N\n",
+      "rho = m*na\n",
+      "\n",
+      "#Result\n",
+      "print \"Number of atoms =\",round((n/1E+29),3),\"*10^29\"\n",
+      "print \"The density of diamond is\",round(rho,1),\"kg/m^3(Calculation mistake in the textbook)\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Number of atoms = 1.773 *10^29\n",
+        "The density of diamond is 3529.4 kg/m^3(Calculation mistake in the textbook)\n"
+       ]
+      }
+     ],
+     "prompt_number": 58
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 2.6, Page number 2.19"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "rho = 2.18  #density of NaCl(gm/cm^3)\n",
+      "N = 6.023*10**23  #Avogadro's number(/mol)\n",
+      "\n",
+      "#Caculations\n",
+      "w = 23+35.5  #molecular weight of NaCl\n",
+      "m = w/N      #mass of NaCl molecule\n",
+      "nm = rho/m    #no. of molecules per unit volume(molecule/cm^3)\n",
+      "#Since NaCl is diatomic\n",
+      "n = 2*nm\n",
+      "#Let a be the distance between adjacent atoms in NaCl and\n",
+      "#    n be the no. of atoms along the edge of the cube\n",
+      "#length of an edge = na\n",
+      "#volume of unit cube = n^3*a^3\n",
+      "a = (1/n)**(1./3.)\n",
+      "\n",
+      "#Result\n",
+      "print \"The distance between two adjacent atoms is\",round((a/1E-8),2),\"A\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The distance between two adjacent atoms is 2.81 A\n"
+       ]
+      }
+     ],
+     "prompt_number": 4
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 2.7, Page number 2.20"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "from math import sqrt\n",
+      "\n",
+      "#Variable declaration\n",
+      "w = 63.5           #atomic weight of copper\n",
+      "r = 1.278*10**-8   #atomic rdius(m)\n",
+      "N = 6.023*10**23   #Avogadro's number(/mol)\n",
+      "\n",
+      "#Calculations\n",
+      "m = w/N    #mass of each copper atom(gm)\n",
+      "#Since copper has FCC structure lattice constant\n",
+      "a = (4*r)/sqrt(2) \n",
+      "n = 4      #no. of atoms in unit cell of FCC structure\n",
+      "M = n*m    #mass of unit cell\n",
+      "rho = M/a**3  #density\n",
+      "\n",
+      "#Result\n",
+      "print \"Density of copper =\",round(rho,2),\"gm/cm^3\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Density of copper = 8.93 gm/cm^3\n"
+       ]
+      }
+     ],
+     "prompt_number": 3
+    }
+   ],
+   "metadata": {}
+  }
+ ]
+}
\ No newline at end of file
diff --git a/Solid_state_physics/Chapter_3.ipynb b/Solid_state_physics/Chapter_3.ipynb
new file mode 100755
index 00000000..c7c45c55
--- /dev/null
+++ b/Solid_state_physics/Chapter_3.ipynb
@@ -0,0 +1,459 @@
+{
+ "metadata": {
+  "name": "",
+  "signature": "sha256:201c0242c8a2063b9a355e5a7deec7582a5a21b0e1187464be6b9fa32a384889"
+ },
+ "nbformat": 3,
+ "nbformat_minor": 0,
+ "worksheets": [
+  {
+   "cells": [
+    {
+     "cell_type": "heading",
+     "level": 1,
+     "metadata": {},
+     "source": [
+      "Chapter 3:Crystal planes and X-ray diffraction"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 3.2, Page number 3.5"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "import math\n",
+      "from sympy import *\n",
+      "\n",
+      "#Variable declaration\n",
+      "'''In a simple cubic structure, there are three types of atomic arrangement\n",
+      "(i)(100)\n",
+      "(ii)(110)\n",
+      "(iii)(111)'''\n",
+      "\n",
+      "#Calculations and results\n",
+      "\n",
+      "#Consider (100) plane\n",
+      "n = (1./4.)*4  #no. of atoms in this plane\n",
+      "#Let a be the lattice constant in mm\n",
+      "a = Symbol('a')\n",
+      "A1 = a**2\n",
+      "nm = n/A1     #no. of atoms per mm^2\n",
+      "print \"The number of atoms per square millimeter for (100) plane is\",nm\n",
+      "\n",
+      "#Consider (110) plane\n",
+      "n2 = 1    \n",
+      "A2 = math.sqrt(2)*a**2\n",
+      "nm2 = n2/A2\n",
+      "print \"The number of atoms per square millimeter for (110) plane is\",nm2\n",
+      "\n",
+      "#Consider (111) plane\n",
+      "n3 = (1./360.)*60*3\n",
+      "EO = a*math.sqrt(2)*math.cos(math.pi/6)\n",
+      "A3 = (a*math.sqrt(2)*EO)/2\n",
+      "nm3 = n3/A3\n",
+      "print \"The number of atoms per square millimeter for (111) plane is\",nm3"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The number of atoms per square millimeter for (100) plane is 1.0/a**2\n",
+        "The number of atoms per square millimeter for (110) plane is 0.707106781186547/a**2\n",
+        "The number of atoms per square millimeter for (111) plane is 0.577350269189626/a**2\n"
+       ]
+      }
+     ],
+     "prompt_number": 2
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 3.3, Page number 3.6"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "from math import sqrt\n",
+      "\n",
+      "#Variable declartion\n",
+      "r = 0.1278*10**-9  #atomic radius(m)\n",
+      "\n",
+      "#Calculations\n",
+      "#For FCC structure,\n",
+      "a = (4*r)/sqrt(2)\n",
+      "\n",
+      "#For (110) plane,\n",
+      "h1 = 1\n",
+      "k1 = 1\n",
+      "l1 = 0\n",
+      "d1 = a/((h1**2+k1**2+l1**2)**0.5) \n",
+      "\n",
+      "#For (212) plane,\n",
+      "h2 = 2\n",
+      "k2 = 1\n",
+      "l2 = 2\n",
+      "d2 = a/((h2**2+k2**2+l2**2)**0.5)\n",
+      "\n",
+      "#Results\n",
+      "print \"Interplanar spacing for (110) plane =\",d1/1E-9,\"nm\"\n",
+      "print \"Interplanar spacing for (212) plane =\",round((d2/1E-9),4),\"nm\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Interplanar spacing for (110) plane = 0.2556 nm\n",
+        "Interplanar spacing for (212) plane = 0.1205 nm\n"
+       ]
+      }
+     ],
+     "prompt_number": 3
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 3.4, Page number 3.7"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "from sympy import *\n",
+      "\n",
+      "#Variable declaration\n",
+      "#Let a be the lattice constant\n",
+      "#For calculations, let us assume a = 1\n",
+      "a = 1\n",
+      "\n",
+      "#Calculations\n",
+      "\n",
+      "#For (100) plane,\n",
+      "h1 = 1\n",
+      "k1 = 0\n",
+      "l1 = 0\n",
+      "d1 = 1/((h1**2+k1**2+l1**2)**0.5) \n",
+      "\n",
+      "#For (110) plane,\n",
+      "h2 = 1\n",
+      "k2 = 1\n",
+      "l2 = 0\n",
+      "d2 = 1/((h2**2+k2**2+l2**2)**0.5)\n",
+      "\n",
+      "#For (111) plane,\n",
+      "h3 = 1\n",
+      "k3 = 1\n",
+      "l3 = 1\n",
+      "d3 = 1/((h3**2+k3**2+l3**2)**0.5)\n",
+      "\n",
+      "#Result\n",
+      "print \"d100:d110:d111 =\",d1,\":\",d2,\":\",d3"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "d100:d110:d111 = 1.0 : 0.707106781187 : 0.57735026919\n"
+       ]
+      }
+     ],
+     "prompt_number": 4
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 3.5, Page number 3.7"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "#Coefficients of intercepts along three axes\n",
+      "m = 1.\n",
+      "n = 1./2.\n",
+      "p = 3.\n",
+      "\n",
+      "#Calculations\n",
+      "m_inv = 1/m        \n",
+      "n_inv = 1/n\n",
+      "p_inv = 1/p\n",
+      "\n",
+      "def gcd(a, b):\n",
+      "    while b:      \n",
+      "        a, b = b, a % b\n",
+      "    return a\n",
+      "\n",
+      "def lcm(a, b):\n",
+      "    return (a * b)/ gcd(a, b)\n",
+      "\n",
+      "def lcmm(*args): \n",
+      "    return reduce(lcm, args)\n",
+      "\n",
+      "mul_fact = lcmm(1,1,3)\n",
+      "m1 = m_inv*mul_fact    #Clear the first fraction\n",
+      "m2 = n_inv*mul_fact    #Clear the second fraction\n",
+      "m3 = p_inv*mul_fact    #Clear the third fraction\n",
+      "print \"The required miller indices are\", m1,m2,m3\n"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The required miller indices are 3.0 6.0 1.0\n"
+       ]
+      }
+     ],
+     "prompt_number": 5
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 3.6, Page number 3.14"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "d = 0.282*10**-9   #lattice spacing(m)\n",
+      "n = 1              #first order\n",
+      "theta = 8.35       #glancing angle(degrees)\n",
+      "\n",
+      "#Calculations\n",
+      "lamda = (2*d*math.sin(math.radians(theta)))/n\n",
+      "\n",
+      "#For maximum value possible,\n",
+      "theta = 90\n",
+      "n = (2*d)/lamda\n",
+      "\n",
+      "#Results\n",
+      "print \"Wavelength of X-rays =\",round((lamda/1E-9),4),\"nm\"\n",
+      "print \"Maximum order of diffraction possible =\",round(n,2)"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Wavelength of X-rays = 0.0819 nm\n",
+        "Maximum order of diffraction possible = 6.89\n"
+       ]
+      }
+     ],
+     "prompt_number": 8
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 3.8, Page number 3.15"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "lamda = 1.5418*10**-10   #wavelength(m)\n",
+      "theta = 30               #angle(degrees)\n",
+      "n = 1                    #first order\n",
+      "#For (111) plane\n",
+      "h = 1\n",
+      "k = 1\n",
+      "l = 1\n",
+      "\n",
+      "#Calculations\n",
+      "d = (n*lamda)/(2*math.sin(math.radians(theta)))\n",
+      "a = d*((h**2+k**2+l**2)**0.5)\n",
+      "\n",
+      "#Result\n",
+      "print \"Interatomic spacing =\",round((a/1E-10),3),\"A\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Interatomic spacing = 2.67 A\n"
+       ]
+      }
+     ],
+     "prompt_number": 9
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 3.9, Page number 3.15"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "from math import sqrt, pi \n",
+      "\n",
+      "#Variable declaration\n",
+      "d = 0.28              #lattice spacing\n",
+      "lamda = 0.074*10**-9  #Wavelength(m)\n",
+      "n = 2                 #2nd order\n",
+      "\n",
+      "#Calculations\n",
+      "d110 = d/sqrt(2)\n",
+      "theta = math.asin((n*lamda)/(2*d110))*180/pi\n",
+      "\n",
+      "#Result\n",
+      "print \"Glancing angle =\",round(theta/1E-9),\"degrees\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Glancing angle = 21.0 degrees\n"
+       ]
+      }
+     ],
+     "prompt_number": 10
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 3.10, Page number 3.16"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "a = 0.38*10**-9  #lattice constant\n",
+      "h = 1\n",
+      "k = 1\n",
+      "l = 0\n",
+      "\n",
+      "#Calculations\n",
+      "d = a/math.sqrt(h**2+k**2+l**2)\n",
+      "\n",
+      "#Result\n",
+      "print \"Distance =\",round((d/1E-9),2),\"nm\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Distance = 0.27 nm\n"
+       ]
+      }
+     ],
+     "prompt_number": 11
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 3.11, Page number 3.16"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "import math\n",
+      "from sympy import *\n",
+      "\n",
+      "#Variable declaration\n",
+      "a = Symbol('a')\n",
+      "\n",
+      "#Calculations\n",
+      "#For (110) plane\n",
+      "a1 = math.sqrt(2)*a**2  #area of plane\n",
+      "n1 = (1./4 )*4          #no. of atoms in this plane\n",
+      "rho1 = n1/a1\n",
+      "\n",
+      "#For (111) plane\n",
+      "EO = (a*math.sqrt(3))/math.sqrt(2)\n",
+      "a2 = (a*EO)/math.sqrt(2)\n",
+      "n2 = 3*(1./6.)\n",
+      "rho2 = n2/a2\n",
+      "\n",
+      "#Result\n",
+      "print \"Density of lattice points (111) plane:density of lattice points (110) plane =\",rho2,\":\",rho1"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Density of lattice points (111) plane:density of lattice points (110) plane = 0.577350269189626/a**2 : 0.707106781186547/a**2\n"
+       ]
+      }
+     ],
+     "prompt_number": 12
+    }
+   ],
+   "metadata": {}
+  }
+ ]
+}
\ No newline at end of file
diff --git a/Solid_state_physics/Chapter_4.ipynb b/Solid_state_physics/Chapter_4.ipynb
new file mode 100755
index 00000000..019aaef9
--- /dev/null
+++ b/Solid_state_physics/Chapter_4.ipynb
@@ -0,0 +1,189 @@
+{
+ "metadata": {
+  "name": "",
+  "signature": "sha256:c896524cb6d8dfdd75df5649979d411984ee380fa5c3cbff49f27851e63b1fb4"
+ },
+ "nbformat": 3,
+ "nbformat_minor": 0,
+ "worksheets": [
+  {
+   "cells": [
+    {
+     "cell_type": "heading",
+     "level": 1,
+     "metadata": {},
+     "source": [
+      "Chapter 4:Defects in Solids"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 4.1, Page number 4.6"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "k = 1.38*10**-23   #Boltzmann constant(eV/K)\n",
+      "e = 1.6*10**-19    #Electronic charge(C)\n",
+      "T1 = 500           #First temperature for metal(K)\n",
+      "T2 = 1000          #Second temperature for metal(K)\n",
+      "Ev = 1             #Average energy required to create a vacancy in metal(eV)\n",
+      "\n",
+      "#Calculations\n",
+      "x = k/e\n",
+      "#n_500 = N*exp(-Ev/T1*k)  ---(1)\n",
+      "#n_1000 = N*exp(-Ev/T2*k) ---(2)\n",
+      "#Dividing (1) by (2), we get the following expression\n",
+      "n = math.exp(Ev/(T2*x))\n",
+      "\n",
+      "#Result\n",
+      "print \"Ratio of vacancies=\",round((n/1E+5),3),\"*10^5\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Ratio of vacancies= 1.085 *10^5\n"
+       ]
+      }
+     ],
+     "prompt_number": 1
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 4.2, Page number 4.7"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "n1_by_N = 1.*10**-10  #frequency of vacancy sites at 500 C\n",
+      "T1 = 500.+273.        #K\n",
+      "T2 = 1000.+273.       #K\n",
+      "\n",
+      "#Calculations\n",
+      "x = math.exp((T1/T2)*math.log(n1_by_N))\n",
+      "\n",
+      "#Result\n",
+      "print \"Frequency of vacancy sites at 1000 C =\",round((x/1E-7),4),\"*10^-7\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Frequency of vacancy sites at 1000 C = 8.467 *10^-7\n"
+       ]
+      }
+     ],
+     "prompt_number": 2
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 4.3, Page number 4.9"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "r = 2.82*10**-10  #interionic distance(m)\n",
+      "n = 5*10**11      #density of Schottky defect(per m^3)\n",
+      "T = 25+273        #temperature(K)\n",
+      "k = 8.625*10**-5  #Boltzmann constant(/K)\n",
+      "\n",
+      "#Calculations\n",
+      "v = (2*r)**3       #volume of one unit cell(m^3)\n",
+      "N = 4/v           #density of ion pairs\n",
+      "Es = 2*k*T*2.303*math.log10(N/n)\n",
+      "\n",
+      "#Result\n",
+      "print \"The average energy required for creation of one Schottky defect is\",round(Es,3),\"eV\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The average energy required for creation of one Schottky defect is 1.971 eV\n"
+       ]
+      }
+     ],
+     "prompt_number": 4
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 4.4, Page number 4.11"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "T1 = 20+273  #K\n",
+      "T2 = 300+273 #K\n",
+      "Ef = 1.4     #average energy for creating a Freknel defect(eV)\n",
+      "k = 8.625*10**-5  #Boltzmann constant(J/K)\n",
+      "N = 1             #For simplicity assume total number of metal ions to be unity\n",
+      "Ni = 1            #For simplicity assume total number of metal ions to be unity\n",
+      "\n",
+      "#Calculations\n",
+      "n1 = (N*Ni)**0.5*math.exp(-Ef/(2*k*T1)) \n",
+      "n2 = (N*Ni)**0.5*math.exp(-Ef/(2*k*T2))      \n",
+      "x = n1/n2\n",
+      "\n",
+      "#Result\n",
+      "print \"The ratio of the number of Frenkel defects is\",round((x/1E-6),2),\"*10^-6 or\",round(((1/x)/1E+5),2),\"*10^5\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The ratio of the number of Frenkel defects is 1.32 *10^-6 or 7.56 *10^5\n"
+       ]
+      }
+     ],
+     "prompt_number": 27
+    }
+   ],
+   "metadata": {}
+  }
+ ]
+}
\ No newline at end of file
diff --git a/Solid_state_physics/Chapter_5.ipynb b/Solid_state_physics/Chapter_5.ipynb
new file mode 100755
index 00000000..42776694
--- /dev/null
+++ b/Solid_state_physics/Chapter_5.ipynb
@@ -0,0 +1,498 @@
+{
+ "metadata": {
+  "name": "",
+  "signature": "sha256:cd8528b1343f720ba16c3255f8c2f531a0d8db6500634023001bba60d12d390a"
+ },
+ "nbformat": 3,
+ "nbformat_minor": 0,
+ "worksheets": [
+  {
+   "cells": [
+    {
+     "cell_type": "heading",
+     "level": 1,
+     "metadata": {},
+     "source": [
+      "Chapter 5:Principles of Quantum Mechanics"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 5.1, Page number 5.12"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Varaible declaration\n",
+      "c = 3*10**8        #velocity of air(m/s)\n",
+      "m = 1.67*10**-27   #mass of proton(kg)\n",
+      "h = 6.626*10**-34  #Planck's constant(J x sec)\n",
+      "\n",
+      "#Calculation\n",
+      "v = c/10.   #velocity of proton(m/s)\n",
+      "lamda = h/(m*v)\n",
+      "\n",
+      "#Result\n",
+      "print \"The de Brogile wavelength is\",round((lamda/1E-14),3),\"*10^-14 m\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The de Brogile wavelength is 1.323 *10^-14 m\n"
+       ]
+      }
+     ],
+     "prompt_number": 1
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 5.2, Page number 5.12"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "import math\n",
+      "\n",
+      "#Varaible declaration\n",
+      "V = 400  #potential(V)\n",
+      "\n",
+      "#Calculation\n",
+      "lamda = 12.26/math.sqrt(V)\n",
+      "\n",
+      "#Result\n",
+      "print \"The de Brogile wavelength is\",lamda,\"A\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The de Brogile wavelength is 0.613 A\n"
+       ]
+      }
+     ],
+     "prompt_number": 2
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 5.3, Page number 5.12"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "import math\n",
+      "\n",
+      "#Varaible declaration\n",
+      "E = 0.025          #kinetic energy of neutron(eV)\n",
+      "m = 1.674*10**-27  #mass of neutron(kg)\n",
+      "h = 6.626*10**-34  #Planck's constant(J x sec)\n",
+      "\n",
+      "#Calculations\n",
+      "E_j = E*1.6*10**-19 #converting eV to joules\n",
+      "lamda = h/math.sqrt(2*m*E_j)\n",
+      "\n",
+      "#Result\n",
+      "print \"The de Brogile wavelength is\",round((lamda/1E-11),3),\"*10^-11 m\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The de Brogile wavelength is 18.106 *10^-11 m\n"
+       ]
+      }
+     ],
+     "prompt_number": 3
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 5.4, Page number 5.13"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "import math\n",
+      "\n",
+      "#Varaible declaration\n",
+      "V = 1600  #potential(V)\n",
+      "\n",
+      "#Calculation\n",
+      "lamda = 12.26/math.sqrt(V)\n",
+      "\n",
+      "#Result\n",
+      "print \"The de Brogile wavelength is\",lamda,\"A\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The de Brogile wavelength is 0.3065 A\n"
+       ]
+      }
+     ],
+     "prompt_number": 4
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 5.5, Page number 5.21"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Varaible declaration\n",
+      "h = 6.626*10**-34  #Planck's constant(J x sec)\n",
+      "m = 9.1*10**-31    #mass of electron(kg)\n",
+      "L = 0.1*10**-9     #length of each side of box(m)\n",
+      "#For lowest energy level,\n",
+      "nx = 1\n",
+      "ny = 1\n",
+      "nz = 1\n",
+      "\n",
+      "#Calculations\n",
+      "E1 = (((h**2)*(nx**2+ny**2+nz**2))/(8*m*L**2))/(1.6*10**-19)\n",
+      "\n",
+      "#Result\n",
+      "print \"The lowest energy of electron is\",round(E1,2),\"eV\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The lowest energy of electron is 113.08 eV\n"
+       ]
+      }
+     ],
+     "prompt_number": 19
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 5.6, Page number 5.22"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "h = 6.626*10**-34  #Planck's constant(J x sec)\n",
+      "m = 9.1*10**-31    #mass of electron(kg)\n",
+      "L = 0.1*10**-9     #length of each side of box(m)\n",
+      "#For level next to lowest energy level,\n",
+      "nx = 1\n",
+      "ny = 1\n",
+      "nz = 2\n",
+      "\n",
+      "#Calculations\n",
+      "E1 = (((h**2)*(nx**2+ny**2+nz**2))/(8*m*L**2))/(1.6*10**-19)\n",
+      "\n",
+      "#Result\n",
+      "print \"The lowest energy of electron is\",round(E1,2),\"eV\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The lowest energy of electron is 226.15 eV\n"
+       ]
+      }
+     ],
+     "prompt_number": 18
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 5.7, Page number 5.23"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "h = 6.626*10**-34  #Planck's constant(J x sec)\n",
+      "m = 9.1*10**-31    #mass of electron(kg)\n",
+      "E = 2000.          #energy of electron(eV)\n",
+      "\n",
+      "#Calculations\n",
+      "Ej = E*1.6*10**-19 #converting eV to joules\n",
+      "lamda = h/math.sqrt(2*m*Ej)\n",
+      "\n",
+      "#Result\n",
+      "print \"The de Brogile wavelength is\",round((lamda/1E-9),4),\"nm\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The de Brogile wavelength is 0.0275 nm\n"
+       ]
+      }
+     ],
+     "prompt_number": 17
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 5.8, Page number 5.23"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "h = 6.626*10**-34  #Planck's constant(J x sec)\n",
+      "m = 9.1*10**-31    #mass of electron(kg)\n",
+      "L = 4*10**-10      #length of each side of box(m)\n",
+      "#For minimum energy \n",
+      "n = 1\n",
+      "\n",
+      "#Calculations\n",
+      "E1 = ((h**2)*(n**2))/(8*m*L**2)\n",
+      "\n",
+      "#Result\n",
+      "print \"Minimum energy =\",round((E1/1E-18),3),\"*10^-18 J\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Minimum energy = 0.377 *10^-18 J\n"
+       ]
+      }
+     ],
+     "prompt_number": 16
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 5.9, Page number 5.24"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "h = 6.626*10**-34  #Planck's constant(J x sec)\n",
+      "m = 9.1*10**-31    #mass of electron(kg)\n",
+      "L = 1*10**-10      #length of each side of box(m)\n",
+      "n1 = 10            #For energy in ground state\n",
+      "n2 = 2             #For energy in first excited state\n",
+      "n3 = 3             #For energy in second excited state\n",
+      "\n",
+      "#Calculations\n",
+      "E1 = ((h**2)*(n1**2))/(8*m*L**2)\n",
+      "E2 = ((h**2)*(n2**2))/(8*m*L**2)\n",
+      "E3 = ((h**2)*(n3**2))/(8*m*L**2)\n",
+      "\n",
+      "#Results\n",
+      "print \"Energy in ground state =\",round((E1/1E-17),4),\"*10^17 J (Calculation mistake in textbook)\"\n",
+      "print \"Energy in first excited state =\",round((E2/1E-17),4),\"*10^17 J\"\n",
+      "print \"Energy in second excited state =\",round((E3/1E-17),4),\"*10^17 J\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Energy in ground state = 60.3075 *10^17 J (Calculation mistake in textbook)\n",
+        "Energy in first excited state = 2.4123 *10^17 J\n",
+        "Energy in second excited state = 5.4277 *10^17 J\n"
+       ]
+      }
+     ],
+     "prompt_number": 21
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 5.10, Page number 5.24"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "h = 6.626*10**-34    #Planck's constant(J x sec)\n",
+      "m = 9.1*10**-31      #mass of electron(kg)\n",
+      "lamda = 1.66*10**-10 #wavelength(m)\n",
+      "\n",
+      "#Calculations\n",
+      "v = h/(m*lamda)\n",
+      "KE = (m*v**2)/(2*1.6*10**-19) #in joules\n",
+      "\n",
+      "#Result\n",
+      "print \"Velocity of electron =\",round((v/1E+7),4),\"*10^7 m\"\n",
+      "print \"Kinetic energy of electron =\",round(KE,2),\"eV\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Velocity of electron = 0.4386 *10^7 m\n",
+        "Kinetic energy of electron = 54.71 eV\n"
+       ]
+      }
+     ],
+     "prompt_number": 22
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 5.11, Page number 5.25"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "import math\n",
+      "\n",
+      "#Varaible declaration\n",
+      "V = 15*10**3  #potential(V)\n",
+      "\n",
+      "#Calculation\n",
+      "lamda = 12.26/math.sqrt(V)\n",
+      "\n",
+      "#Result\n",
+      "print \"The de Brogile wavelength is\",round(lamda,2),\"A\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The de Brogile wavelength is 0.1 A\n"
+       ]
+      }
+     ],
+     "prompt_number": 23
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 5.12, Page number 5.25"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "import math\n",
+      "\n",
+      "#Varaible declaration\n",
+      "V = 344    #potential(V)\n",
+      "theta = 60 #glancing angle(degrees)\n",
+      "\n",
+      "#Calculation\n",
+      "lamda = 12.26/math.sqrt(V)\n",
+      "#For first reflection \n",
+      "n = 1\n",
+      "d = (n*lamda)/(2*math.sin(math.radians(theta)))\n",
+      "\n",
+      "#Result\n",
+      "print \"The interatomic spacing of the crystal is\",round(d,4),\"A\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The interatomic spacing of the crystal is 0.3816 A\n"
+       ]
+      }
+     ],
+     "prompt_number": 24
+    }
+   ],
+   "metadata": {}
+  }
+ ]
+}
\ No newline at end of file
diff --git a/Solid_state_physics/Chapter_6.ipynb b/Solid_state_physics/Chapter_6.ipynb
new file mode 100755
index 00000000..2b4f9a24
--- /dev/null
+++ b/Solid_state_physics/Chapter_6.ipynb
@@ -0,0 +1,386 @@
+{
+ "metadata": {
+  "name": "",
+  "signature": "sha256:425f92ebc94b7b662d737292c7c739a2d9f7bf01d4a0a5239c1380861a6af3a7"
+ },
+ "nbformat": 3,
+ "nbformat_minor": 0,
+ "worksheets": [
+  {
+   "cells": [
+    {
+     "cell_type": "heading",
+     "level": 1,
+     "metadata": {},
+     "source": [
+      "Chapter 6: Electron theory of Metals"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 6.1, Page number 6.5"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "rho_s = 10.5*10**3   #density of silver(kg/m^3)\n",
+      "Na = 6.02*10**26     #Avogadro's number\n",
+      "Ma = 107.9           #atomic weight of silver\n",
+      "sigma = 6.8*10**7    #conductivity(/ohm-m)\n",
+      "e = 1.6*10**-19      #charge of an electron(C)\n",
+      "\n",
+      "#Calculations\n",
+      "n = (rho_s*Na)/Ma\n",
+      "u = sigma/(n*e)\n",
+      "\n",
+      "#Results\n",
+      "print \"Density of electrons =\",round((n/1E+28),2),\"*10^28\"\n",
+      "print \"Mobility of electrons =\",round((u/1E-2),3),\"*10^-2 m^2/V-s\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Density of electrons = 5.86 *10^28\n",
+        "Mobility of electrons = 0.725 *10^-2 m^2/V-s\n"
+       ]
+      }
+     ],
+     "prompt_number": 1
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 6.2, Page number 6.6"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "den = 8.92*10**3  #density(kg/m^3)\n",
+      "rho = 1.73*10**-8 #resistivity of copper(ohm-m)\n",
+      "Ma = 63.5         #atomic weight\n",
+      "e = 1.6*10**-19   #charge of an electron(C)\n",
+      "Na = 6.02*10**26  #Avogadro's number\n",
+      "m = 9.1*10**-31   #mass of an electron(kg)\n",
+      "\n",
+      "#Calculations\n",
+      "n = (den*Na)/Ma\n",
+      "u = 1/(rho*n*e)\n",
+      "tou = m/(n*e**2*rho)\n",
+      "\n",
+      "#Results\n",
+      "print \"Mobility of electrons =\",round((u/1E-2),3),\"*10^-2 m/V-s\"\n",
+      "print \"Average time of collision of electrons =\",round((tou/1E-14),2),\"*10^-14 s\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Mobility of electrons = 0.427 *10^-2 m/V-s\n",
+        "Average time of collision of electrons = 2.43 *10^-14 s\n"
+       ]
+      }
+     ],
+     "prompt_number": 2
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 6.3, Page number 6.7"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "P = 1.54*10**-8    #resistivity(ohm-m)\n",
+      "n = 5.8*10**28     #no. of electrons per m^3\n",
+      "m = 9.108*10**-31  #mass of an elecron(kg)\n",
+      "e = 1.602*10**-19  #charge of an electron(C)\n",
+      "\n",
+      "#Calculations\n",
+      "tou = m/(n*e**2*P)\n",
+      "\n",
+      "#Result\n",
+      "print \"The relaxation time of conducton of electrons is\",round((tou/1E-14),2),\"*10^-14 s\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The relaxation time of conducton of electrons is 3.97 *10^-14 s\n"
+       ]
+      }
+     ],
+     "prompt_number": 3
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 6.4, Page number 6.8"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Varaible declaration\n",
+      "R = 0.06             #resistance(ohms)\n",
+      "D = 5                #length of wire(m)\n",
+      "I = 15               #current(A)\n",
+      "p = 2.7*10**-8       #resistivity of aluminium(ohm-m)\n",
+      "Ma = 26.98           #atomic weight\n",
+      "Na = 6.025*10**26    #Avogadro's number\n",
+      "rho_s = 2.7*10**3    #sensity(kg/m^3)\n",
+      "\n",
+      "#Calculations\n",
+      "#Since each free atom atom contains 3 electrons, therefore,\n",
+      "n = (3*rho_s*Na)/Ma\n",
+      "\n",
+      "#For mobility\n",
+      "u = 1/(n*e*p)\n",
+      "\n",
+      "#For drift velocity\n",
+      "E = (I*R)/D\n",
+      "vd = u*E\n",
+      "\n",
+      "#Results\n",
+      "print \"Free electron concentration =\",round((n/1E+29),4),\"*10^29 electrons/m^2\"\n",
+      "print \"Mobility of electrons =\",round((u/1E-3),3),\"*10^-3 m/V-s\"\n",
+      "print \"Drift velocity of electrons =\",round((vd/1E-3),3),\"*10^-3 m/s\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Free electron concentration = 1.8088 *10^29 electrons/m^2\n",
+        "Mobility of electrons = 1.278 *10^-3 m/V-s\n",
+        "Drift velocity of electrons = 0.23 *10^-3 m/s\n"
+       ]
+      }
+     ],
+     "prompt_number": 5
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 6.5, Page number 6.13"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "L = 0.1*10**-9    #length of each side of box(m)\n",
+      "h = 6.62*10**-34  #Planck's constant(J-s)\n",
+      "m = 9.1*10**-31   #mass of electron(kg)\n",
+      "#For lowest energy,\n",
+      "nx = 1\n",
+      "ny = 1\n",
+      "nz = 1\n",
+      "\n",
+      "#Calculations\n",
+      "E1 = (((h**2)*(nx**2+ny**2+nz**2))/(8*m*L**2))//(1.6*10**-19)\n",
+      "\n",
+      "#Result\n",
+      "print \"The lowest energy of electron is\",round(E1,2),\"eV\" "
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The lowest energy of electron is 112.0 eV\n"
+       ]
+      }
+     ],
+     "prompt_number": 7
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Exmple 6.6, Page number 6.13"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "'''Fermi equation\n",
+      "F(E) =       1\n",
+      "          ---------------\n",
+      "          1+exp((E-Ef)/kT)\n",
+      "Given, E-Ef = kT\n",
+      "therefore,\n",
+      "F(E) =    1\n",
+      "      --------\n",
+      "      1+exp(1)\n",
+      "'''\n",
+      "\n",
+      "#Calculation\n",
+      "Fe = 1./(1.+math.exp(1.))\n",
+      "\n",
+      "#Result\n",
+      "print \"F(E) =\",round(Fe,3)"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "F(E) = 0.269\n"
+       ]
+      }
+     ],
+     "prompt_number": 8
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 6.7, Page number 6.13"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "import math \n",
+      "\n",
+      "#Variable declaration\n",
+      "Fe = 10./100.   #probability\n",
+      "Ef = 5.5        #Fermi energy(eV)\n",
+      "k = 1.38*10**-23\n",
+      " \n",
+      "#Calculations\n",
+      "'''Fermi equation\n",
+      "F(E) =       1\n",
+      "          ---------------\n",
+      "          1+exp((E-Ef)/kT)\n",
+      "'''\n",
+      "E = Ef+(Ef/100)\n",
+      "E_Ef = (E - Ef)*1.6*10**-19  #(J)\n",
+      "\n",
+      "#Let x be E-Ef/k\n",
+      "x = E_Ef/k\n",
+      "T = x/math.log(-(1-(1/Fe)))\n",
+      "\n",
+      "#Result\n",
+      "print \"Temperature =\",round(T,2),\"K\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Temperature = 290.22 K\n"
+       ]
+      }
+     ],
+     "prompt_number": 9
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 6.8, Page number 6.16"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "import math \n",
+      "\n",
+      "#Variable declaration\n",
+      "Fe = 1./100.   #probability\n",
+      "Ef = 0.5       #Fermi energy(eV)\n",
+      "k = 1.38*10**-23\n",
+      " \n",
+      "#Calculations\n",
+      "'''Fermi equation\n",
+      "F(E) =       1\n",
+      "          ---------------\n",
+      "          1+exp((E-Ef)/kT)\n",
+      "'''\n",
+      "\n",
+      "E = Ef+0.5\n",
+      "E_Ef = (E - Ef)*1.6*10**-19  #(J)\n",
+      "\n",
+      "#Let x be E-Ef/k\n",
+      "x = E_Ef/k\n",
+      "T = x/math.log(-(1-(1/Fe)))\n",
+      "\n",
+      "#Result\n",
+      "print \"Temperature =\",round(T),\"K\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Temperature = 1262.0 K\n"
+       ]
+      }
+     ],
+     "prompt_number": 10
+    }
+   ],
+   "metadata": {}
+  }
+ ]
+}
\ No newline at end of file
diff --git a/Solid_state_physics/Chapter_7.ipynb b/Solid_state_physics/Chapter_7.ipynb
new file mode 100755
index 00000000..c3599dfb
--- /dev/null
+++ b/Solid_state_physics/Chapter_7.ipynb
@@ -0,0 +1,330 @@
+{
+ "metadata": {
+  "name": "",
+  "signature": "sha256:9ccabd1c0a5d5861a1e63defe760a8b9caed49864d9aebb3ab3b0741ed755b61"
+ },
+ "nbformat": 3,
+ "nbformat_minor": 0,
+ "worksheets": [
+  {
+   "cells": [
+    {
+     "cell_type": "heading",
+     "level": 1,
+     "metadata": {},
+     "source": [
+      "Chapter 7: Dielectric Properties"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 7.1, Page number 7.23"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "C = 2*10**-6   #Capacitance(F)\n",
+      "V = 1000       #voltage(V)\n",
+      "Er = 100       #permittivity\n",
+      "\n",
+      "#Calculations\n",
+      "W = (C*V**2)/2\n",
+      "\n",
+      "Co = C/Er\n",
+      "Wo = (Co*V**2)/2\n",
+      "Wf = W-Wo\n",
+      "\n",
+      "#Result\n",
+      "print \"Energy stored in condenser =\",W,\"J\"\n",
+      "print \"Energy stored in polarizing the dilectric =\",Wf,\"J\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Energy stored in condenser = 1.0 J\n",
+        "Energy stored in polarizing the dilectric = 0.99 J\n"
+       ]
+      }
+     ],
+     "prompt_number": 1
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 7.2, Page number 7.24"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaraion\n",
+      "Er = 4.94   #permittivity\n",
+      "n2 = 2.69   #index of refraction\n",
+      "\n",
+      "#Calculations\n",
+      "'''\n",
+      "Er - 1    N(ae+ai)\n",
+      "------ = ---------\n",
+      "Er + 2     3*Eo \n",
+      "Sunbstituting the values for Er, we get,\n",
+      "N(ae+ai)       \n",
+      "--------  = 0.5677           ------------(1)\n",
+      "  3*ao\n",
+      "'''\n",
+      "x = 0.5677\n",
+      "\n",
+      "'''\n",
+      "Also, Er = n**2\n",
+      "Therefore, n**2-1    N*ae\n",
+      "           ------- = -----\n",
+      "            n**2+2    3*Eo\n",
+      "Substituting the values for n^2, we get,\n",
+      "N*ae\n",
+      "---- = 0.36034   ---------------(2)\n",
+      "3*Eo\n",
+      "'''\n",
+      "y = 0.36034\n",
+      "#Let z = ai/ae\n",
+      "#Dividing equation (1) by (2), we get,\n",
+      "\n",
+      "z = (x/y)-1\n",
+      "\n",
+      "#Result\n",
+      "print \"Ratio between electronic and ionic probabbility is\",round(z,3) ,\"or\",round((1/z),3)\n"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Ratio between electronic and ionic probabbility is 0.575 or 1.738\n"
+       ]
+      }
+     ],
+     "prompt_number": 5
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 7.3, Page number 7.25"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "Er = 2.56         #permittivity\n",
+      "f = 1*10**6       #frequency(Hz)\n",
+      "A = 8*10**-4      #area(m^2)\n",
+      "d= 0.08*10**-3    #distance of seperation(m)\n",
+      "Eo = 8.85*10**-12\n",
+      "\n",
+      "#Calculations\n",
+      "Er_dash = Er*0.7*10**-4\n",
+      "w = 2*math.pi*f\n",
+      "Rp = d/(w*Eo*Er_dash*A)\n",
+      "\n",
+      "Cp = (A*Eo*Er)/d\n",
+      "\n",
+      "#Results\n",
+      "print \"Parallel loss resistance =\",round((Rp/1E+6),2),\"MOhms\"\n",
+      "print \"Capacitance =\",Cp,\"F(Calculation mistake in textbook)\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Parallel loss resistance = 10.04 MOhms\n",
+        "Capacitance = 2.2656e-10 F(Calculation mistake in textbook)\n"
+       ]
+      }
+     ],
+     "prompt_number": 6
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 7.5, Page number 7.26"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Varaible declaration\n",
+      "N = 3.*10**28       #density(atoms/m^3)\n",
+      "ae = 10.**-40       #electronic polarizability(F m^2)\n",
+      "Eo = 8.854*10**-12  #permittivity of free space(F/m)\n",
+      "\n",
+      "#Calculaion\n",
+      "Er = 1+((N*ae)/Eo)\n",
+      "\n",
+      "#Result\n",
+      "print \"dielectric constant =\",round(Er,3)"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "dielectric constant = 1.339\n"
+       ]
+      }
+     ],
+     "prompt_number": 7
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 7.5, Page number 7.26"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "Er = 1.0000684      #permittivity of dilectric\n",
+      "Eo = 8.854*10**-12  #permittivity of free space(F/m)\n",
+      "N = 2.7*10**25      #density(atoms/m^3)\n",
+      "\n",
+      "#Calculation\n",
+      "ae = (Eo*(Er-1))/N\n",
+      "\n",
+      "#Result\n",
+      "print \"Electronic polarizability =\",round((ae/1E-41),3),\"*10^-41 Fm^2\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Electronic polarizability = 2.243 *10^-41 Fm^2\n"
+       ]
+      }
+     ],
+     "prompt_number": 8
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 7.6, Page number 7.27"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "A = 100*10**-4      #area of parallel capacitor(m^2)\n",
+      "d = 1*10**-2        #separation between plates(m)\n",
+      "Eo = 8.854*10**-12  #permittivity of free space(F/m)\n",
+      "V = 100             #voltage(V)\n",
+      "\n",
+      "#Calculation\n",
+      "C = (Eo*A)/d\n",
+      "Q = C*V\n",
+      "\n",
+      "#Result\n",
+      "print \"Capacitance =\",round((C/1E-12),2),\"pF\"\n",
+      "print \"Charge =\",Q,\"C\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Capacitance = 8.85 pF\n",
+        "Charge = 8.854e-10 C\n"
+       ]
+      }
+     ],
+     "prompt_number": 10
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 7.7, Page number 7.28"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "N = 6.02*10**26    #Avogadro's number\n",
+      "den = 2050         #density(kg/m^3)\n",
+      "Ma = 32            #atomic weight\n",
+      "Eo = 8.55*10**-12 #permittivity of free space(F/m)\n",
+      "v = 1/3            #internal field constant\n",
+      "Er = 3.75          #dielectric constant of sulphur\n",
+      "\n",
+      "#Calculations\n",
+      "n = (N*den)/Ma     #no. of atoms per m^3\n",
+      "ae = ((Er-1)/(Er+2))*((3*Eo)/n)\n",
+      "\n",
+      "#Result\n",
+      "print \"Electronic polarizability =\",round((ae/1E-40),3),\"*10^-41 Fm^2\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Electronic polarizability = 3.181 *10^-41 Fm^2\n"
+       ]
+      }
+     ],
+     "prompt_number": 11
+    }
+   ],
+   "metadata": {}
+  }
+ ]
+}
\ No newline at end of file
diff --git a/Solid_state_physics/Chapter_8.ipynb b/Solid_state_physics/Chapter_8.ipynb
new file mode 100755
index 00000000..161a8521
--- /dev/null
+++ b/Solid_state_physics/Chapter_8.ipynb
@@ -0,0 +1,436 @@
+{
+ "metadata": {
+  "name": "",
+  "signature": "sha256:fbb68fbb0713029438d419fcf28fa2bcf0bc60f8a093b90691d3e7397e7a942d"
+ },
+ "nbformat": 3,
+ "nbformat_minor": 0,
+ "worksheets": [
+  {
+   "cells": [
+    {
+     "cell_type": "heading",
+     "level": 1,
+     "metadata": {},
+     "source": [
+      "Chapter 8:Magnetic Properties"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 8.1, Page number 8.3"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "M = 1.4        #value of magnetic field when filled with iron\n",
+      "H = 6.5*10**-4 #value of magnetic field in the interior\n",
+      "\n",
+      "#Calculations\n",
+      "x = M/H\n",
+      "ur = 1+x\n",
+      "\n",
+      "#Result\n",
+      "print \"Relative permeability of iron is\",round(ur,2),\"(Calculation mistake in textbook)\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Relative permeability of iron is 2154.85 (Calculation mistake in textbook)\n"
+       ]
+      }
+     ],
+     "prompt_number": 1
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 8.2, Page number 8.3"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "M = 3300    #value of magnetic filed(amp/m) \n",
+      "H = 220     #strength of magnetic filed(amp/m)\n",
+      "\n",
+      "#Calculations\n",
+      "x = (M/H)+1\n",
+      "\n",
+      "#Result\n",
+      "print \"Relative permeability of iron is\",round(x,2)"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Relative permeability of iron is 16.0\n"
+       ]
+      }
+     ],
+     "prompt_number": 2
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 8.3, Page number 8.4"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "from math import pi\n",
+      "\n",
+      "#Variable declaration\n",
+      "H = 10**6        #magnetic field intensity(amp/m)\n",
+      "x = 1.5*10**-3   #susceptibility\n",
+      "Uo = 4*pi*10**-7 \n",
+      "\n",
+      "#Calculations\n",
+      "M = x*H       #magnetization of material\n",
+      "B = Uo*(M+H)  #flux density\n",
+      "\n",
+      "#Result\n",
+      "print \"Magnetization =\",round((M/1E+3),1),\"*10^3 A/m\"\n",
+      "print \"Flux density =\",round(B,3),\"T\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Magnetization = 1.5 *10^3 A/m\n",
+        "Flux density = 1.259 T\n"
+       ]
+      }
+     ],
+     "prompt_number": 4
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 8.4, Page number 8.4"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "from math import pi\n",
+      "\n",
+      "#Variable declaration\n",
+      "H = 10**4        #magnetic field intensity(amp/m)\n",
+      "x = 3.7*10**-3   #susceptibility\n",
+      "Uo = 4*pi*10**-7 \n",
+      "\n",
+      "#Calculations\n",
+      "M = x*H       #magnetization of material\n",
+      "B = Uo*(M+H)  #flux density\n",
+      "\n",
+      "#Result\n",
+      "print \"Magnetization =\",M,\"A/m\"\n",
+      "print \"Flux density =\",round(B,4),\"wb/m^2\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Magnetization = 37.0 A/m\n",
+        "Flux density = 0.0126 wb/m^2\n"
+       ]
+      }
+     ],
+     "prompt_number": 5
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 8.5, Page number 8.14"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "from math import pi\n",
+      "\n",
+      "#Variable declaration\n",
+      "I = 500*10**-3  #current(A)\n",
+      "d = 10*10**-2   #diameter of loop(m)\n",
+      "\n",
+      "#Calculations\n",
+      "r = d/2         #radius(m)\n",
+      "A = 2*pi*r**2   #area(m^2)\n",
+      "Um = I*A\n",
+      "\n",
+      "#Result\n",
+      "print \"Magnetic moment =\",round((Um/1E-3),3),\"*10^-3 A-m^2\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Magnetic moment = 7.854 *10^-3 A-m^2\n"
+       ]
+      }
+     ],
+     "prompt_number": 6
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 8.6, Page number 8.18"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "r = 5.29*10**-11  #radius of the orbit(m)\n",
+      "B = 2             #field strength(Tesla)\n",
+      "e = 1.602*10**-19 #charge of an electron(C)\n",
+      "m = 9.108*10**-31 #mass of an electron(kg)\n",
+      "\n",
+      "#Calculation\n",
+      "Uind = (e**2*r**2*B)/(4*m)\n",
+      "\n",
+      "#Result\n",
+      "print \"Change in magnetic moment =\",round((Uind/1E-29),3),\"*10^-29 A-m^2\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Change in magnetic moment = 3.943 *10^-29 A-m^2\n"
+       ]
+      }
+     ],
+     "prompt_number": 7
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 8.7, Page number 8.22"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Varaible declaration\n",
+      "T1 = 350         #temperature(K)\n",
+      "x1 = 2.8*10**-4  #susceptibility at T1\n",
+      "T2 = 300         #temperature(K)\n",
+      "\n",
+      "#Calculation\n",
+      "x2 = (x1*T1)/T2\n",
+      "\n",
+      "#Result\n",
+      "print \"Susceptibility at 300k is\",round((x2/1E-4),3),\"*10^-4\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Susceptibility at 300k is 3.267 *10^-4\n"
+       ]
+      }
+     ],
+     "prompt_number": 8
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 8.8, Page number 8.27"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "from math import pi \n",
+      "\n",
+      "#Variable declaration\n",
+      "den = 8906          #density of nickel(kg/m^3)\n",
+      "N = 6.025*10**26    #Avogadro's number\n",
+      "Ma = 58.7           #atomic weight\n",
+      "Bs = 0.65           #magnetic induction(wb/m^2)\n",
+      "Uo = 4*pi*10**-7\n",
+      "\n",
+      "#Calculations\n",
+      "n = (den*N)/Ma      #no. of nickel atoms per m^3\n",
+      "\n",
+      "#Since x is very large, B = n*Uo*Um\n",
+      "Um = Bs/(n*Uo))\n",
+      "\n",
+      "#Result\n",
+      "print \"Magnetic moment =\",Um,\"A-m^2\"\n"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Magnetic moment = 5.65850692635e-24 A-m^2\n"
+       ]
+      }
+     ],
+     "prompt_number": 10
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 8.9, Page number 8.28"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "H = 2         #magnetic filed intensity(wb/m^2)\n",
+      "U = 9.4*10**-24\n",
+      "k = 1.38*10**-23\n",
+      "\n",
+      "#Calculations\n",
+      "'''\n",
+      "n = c*no*exp(-Eg/kT)   #no. of electrons\n",
+      "where Eg = -U*H\n",
+      "For parallel orientation,Eg = -U*H\n",
+      "For antiparallel orientation, Eg = U*H\n",
+      "therefore,\n",
+      "np = c*no*exp(U*H/kT)  ---(1)\n",
+      "na = c*no*exp(-U*H/kT) ---(2)\n",
+      "Dividing (1) by (2), we get,'''\n",
+      "\n",
+      "T = (2*U*H)/(math.log(2)*k)\n",
+      "\n",
+      "#Result\n",
+      "print \"T=\",round(T,1),\"K\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "T= 3.9 K\n"
+       ]
+      }
+     ],
+     "prompt_number": 34
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 8.10, Page number 8.29"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "from math import pi\n",
+      "\n",
+      "#Variable declaration\n",
+      "Uo = 4*pi*10**-7\n",
+      "Ma = 157.26       #atomic weight og gadolinium\n",
+      "den = 7.8*10**3   #density(kg/m^3)\n",
+      "N = 6.025*10**26  #Avogadro's number\n",
+      "x = 7.1           #Bohr magnetron per atom\n",
+      "Um = 9.27*10**-24\n",
+      "\n",
+      "#Calculations\n",
+      "n = (den*N)/Ma    #no. of atoms in 1 kg\n",
+      "n1 = n*10**-3     #no. of atoms in 1 gm\n",
+      "M = n1*x*Um         #magnetic moment per gram(a-m^2)\n",
+      "\n",
+      "Bs = n*Uo*Um      #saturization magnetization\n",
+      "\n",
+      "#Result\n",
+      "print \"Magnetic moment per gram =\",round(M,3),\"Am^2\"\n",
+      "print \"Saturization magnetization =\",round(Bs,3),\"Wb/m^2(Calculation mistake in textbok)\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Magnetic moment per gram = 1966.851 Am^2\n",
+        "Saturization magnetization = 0.348 Wb/m^2(Calculation mistake in textbok)\n"
+       ]
+      }
+     ],
+     "prompt_number": 41
+    }
+   ],
+   "metadata": {}
+  }
+ ]
+}
\ No newline at end of file
diff --git a/Solid_state_physics/Chapter_9.ipynb b/Solid_state_physics/Chapter_9.ipynb
new file mode 100755
index 00000000..70a3843c
--- /dev/null
+++ b/Solid_state_physics/Chapter_9.ipynb
@@ -0,0 +1,845 @@
+{
+ "metadata": {
+  "name": "",
+  "signature": "sha256:b86f6f4d444d5177f7a40efe10b2b4ac505571f2f5cf98eeaa6619afa2ee7d22"
+ },
+ "nbformat": 3,
+ "nbformat_minor": 0,
+ "worksheets": [
+  {
+   "cells": [
+    {
+     "cell_type": "heading",
+     "level": 1,
+     "metadata": {},
+     "source": [
+      "Chapter 9: Semiconductors"
+     ]
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 9.1, Page number 9.11"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "ni = 2.37*10**19     #intrinsic carrier density(m^-3)\n",
+      "ue = 0.38            #electron mobility(m^2/V-s)\n",
+      "uh = 0.18            #hole mobility(m^2/V-s)\n",
+      "e = 1.6*10**-19      #charge on electron(C)\n",
+      "\n",
+      "#Calculations\n",
+      "sigma_i = ni*e*(ue+uh) #(1/ohm-m)\n",
+      "p = 1/sigma_i\n",
+      "\n",
+      "#Result\n",
+      "print \"Resistivity =\",round(p,3),\"m\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Resistivity = 0.471 m\n"
+       ]
+      }
+     ],
+     "prompt_number": 1
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 9.2, Page number 9.12"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "import math\n",
+      "\n",
+      "#Variable declaration\n",
+      "Eg = 1.12           #bandgap(eV)\n",
+      "k = 1.38*10**-23    #Boltzman constant(J/K)\n",
+      "T = 300             #Temperature(K)\n",
+      "mh = 0.28           #Effective Mass of the hole(kg)\n",
+      "me = 0.12           #Effective Mass of the hole(kg)\n",
+      "e = 1.6*10**-19     #charge on electron(C)\n",
+      "\n",
+      "#Calculation\n",
+      "Ef = (Eg/2)+3/4*k*T*(math.log(mh/me))/e\n",
+      "\n",
+      "#Result \n",
+      "print \"The position of the Fermi level is at\",round(Ef,2),\"from the top of valence band\" "
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The position of the Fermi level is at 0.56 from the top of valence band\n"
+       ]
+      }
+     ],
+     "prompt_number": 2
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 9.3, Page number 9.12"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "from math import pi, exp\n",
+      "\n",
+      "#Variable declaration\n",
+      "m = 9.109*10**-31   #mass of an electron(kg)\n",
+      "k = 1.38*10**-23    #Boltzman constant(J/K)\n",
+      "T = 300             #Temperature(K)\n",
+      "h = 6.626*10**-34   #Planck's constant\n",
+      "Eg = 0.7            #bandgap(eV)\n",
+      "e = 1.6*10**-19     #charge on electron(C)\n",
+      "\n",
+      "#Calculation\n",
+      "C = (((2*pi*m*k)/h**2)**(3./2.))  \n",
+      "T1 = T**(3./2.)\n",
+      "E = exp((-Eg*e)/(2*k*T))\n",
+      "ni = 2*C*T1*E\n",
+      "\n",
+      "#Result\n",
+      "print \"Concentration of intrinsic charge carriers =\",round((ni/1E+18),2),\"*10**18/m^3\"\n"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Concentration of intrinsic charge carriers = 33.48 *10**18/m^3\n"
+       ]
+      }
+     ],
+     "prompt_number": 3
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 9.4, Page number "
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "ni = 2.4*10**19      #intrinsic carrier density(m^-3)\n",
+      "ue = 0.39            #electron mobility(m^2/V-s)\n",
+      "uh = 0.19            #hole mobility(m^2/V-s)\n",
+      "e = 1.6*10**-19      #charge on electron(C)\n",
+      "\n",
+      "#Calculations\n",
+      "sigma_i = ni*e*(ue+uh) #(1/ohm-m)\n",
+      "p = 1/sigma_i\n",
+      "\n",
+      "#Result\n",
+      "print \"Resistivity =\",round(p,3),\"m\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Resistivity = 0.449 m\n"
+       ]
+      }
+     ],
+     "prompt_number": 4
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 9.5, Page number 9.13"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "ni = 2.5*10**19      #intrinsic carrier density(m^-3)\n",
+      "ue = 0.39            #electron mobility(m^2/V-s)\n",
+      "uh = 0.19            #hole mobility(m^2/V-s)\n",
+      "e = 1.6*10**-19      #charge on electron(C)\n",
+      "l = 1*10**-2         #length of rod(m)\n",
+      "A = 10**-3*10**-3    #area(m^2)\n",
+      "\n",
+      "#Calculations\n",
+      "sigma = ni*e*(ue+uh) #(1/ohm-m)\n",
+      "R = 1/(sigma*A)\n",
+      "\n",
+      "#Result\n",
+      "print \"Resistivity =\",round(R,3),\"Ohms\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Resistivity = 431034.483 Ohms\n"
+       ]
+      }
+     ],
+     "prompt_number": 6
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 9.6, Page number 9.14"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "from math import pi, exp\n",
+      "\n",
+      "#Variable declaration\n",
+      "ue = 0.48            #electron mobility(m^2/V-s)\n",
+      "uh = 0.013           #hole mobility(m^2/V-s)\n",
+      "Eg = 1.1             #bandgap(eV)\n",
+      "T = 300              #assumption - Temperature(K)\n",
+      "h = 6.626*10**-34    #Planck's constant\n",
+      "e = 1.6*10**-19      #charge on electron(C)\n",
+      "k = 1.38*10**-23     #Boltzman constant(J/K)\n",
+      "m = 9.1*10**-31      #mass of an electron(kg)\n",
+      "\n",
+      "#Calculation\n",
+      "C = 2*(((2*pi*m*k)/h**2))**(3./2.)\n",
+      "ni = C*T**(3./2.)*exp((-Eg*e)/(2*k*T))\n",
+      "sigma_i =  ni*e*(ue+uh)\n",
+      "\n",
+      "#Result\n",
+      "print \"Conductivity=\",round((sigma_i/1E-3),3),\"*10^-3/ohm-m\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Conductivity= 1.159 *10^-3/ohm-m\n"
+       ]
+      }
+     ],
+     "prompt_number": 7
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 9.7, Page number 9.15"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "from math import pi, exp\n",
+      "\n",
+      "#Variable declaration\n",
+      "ue = 0.4             #electron mobility(m^2/V-s)\n",
+      "uh = 0.2             #hole mobility(m^2/V-s)\n",
+      "Eg = 0.7             #bandgap(eV)\n",
+      "T = 300              #assumption - Temperature(K)\n",
+      "h = 6.626*10**-34    #Planck's constant\n",
+      "e = 1.6*10**-19      #charge on electron(C)\n",
+      "k = 1.38*10**-23     #Boltzman constant(J/K)\n",
+      "m = 9.1*10**-31      #mass of an electron(kg)\n",
+      "\n",
+      "#Calculation\n",
+      "C = 2*(((2*pi*m*k)/h**2))**(3./2.)\n",
+      "ni = C*T**(3./2.)*exp((-Eg*e)/(2*k*T))\n",
+      "sigma_i =  ni*e*(ue+uh)\n",
+      "\n",
+      "#Result\n",
+      "print \"Intrinsic carrier density =\",round((ni/1E+19),2),\"*10^19 per m^3\"\n",
+      "print \"Conductivity=\",round(sigma_i,2),\"/ohm-m\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Intrinsic carrier density = 3.34 *10^19 per m^3\n",
+        "Conductivity= 3.21 /ohm-m\n"
+       ]
+      }
+     ],
+     "prompt_number": 8
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 9.8, Page number 9.15"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "ue = 0.36            #electron mobility(m^2/V-s)\n",
+      "uh = 0.17            #hole mobility(m^2/V-s)\n",
+      "P = 2.12             #resistivity(ohm-m)\n",
+      "e = 1.6*10**-19      #charge on electron(C)\n",
+      "k = 1.38*10**-23     #Boltzman constant(J/K)\n",
+      "m = 9.1*10**-31      #mass of an electron(kg)\n",
+      "h = 6.626*10**-34    #Planck's constant\n",
+      "T = 300              #assumption - Temperature(K)\n",
+      "\n",
+      "#Calculations\n",
+      "sigma = 1/P\n",
+      "ni = sigma/(e*(ue+uh))\n",
+      "C = 2*(((2*pi*m*k)/h**2))**(3./2.)\n",
+      "Eg = ((2*k*T)/e)*math.log(C*(T**(3./2.))/ni)\n",
+      "\n",
+      "#Result\n",
+      "print \"Forbidden energy gap =\",round(Eg,3),\"eV\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Forbidden energy gap = 0.793 eV\n"
+       ]
+      }
+     ],
+     "prompt_number": 9
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 9.9, Page number 9.16"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "from math import log10\n",
+      "\n",
+      "#Variable declaration\n",
+      "p1 = 2        #resistivity(ohm-m)\n",
+      "p2 = 4.5      #resistivity(ohm-m)\n",
+      "T1 = 20.+273  #Temperature(K)\n",
+      "T2 = 32.+273  #temperature(K)\n",
+      "k = 1.38*10**-23     #Boltzman constant(J/K)\n",
+      "\n",
+      "#Calculations\n",
+      "dy = log10(p2)-log10(p1)\n",
+      "dx = (1/T1)-(1/T2)\n",
+      "dy_by_dx = dy/dx\n",
+      "Eg = (2*k*dy_by_dx)/e\n",
+      "\n",
+      "#Result\n",
+      "print \"Energy band gap =\",round(Eg,3),\"eV\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Energy band gap = 0.452 eV\n"
+       ]
+      }
+     ],
+     "prompt_number": 10
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 9.10, Page number 9.16"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "from math import log\n",
+      "\n",
+      "#Variable declaration\n",
+      "e = 1.602*10**-19    #charge on electron(C)\n",
+      "k = 1.38*10**-23     #Boltzman constant(J/K)\n",
+      "Eg = 1*e             #bandgap(J)\n",
+      "\n",
+      "#Calculations\n",
+      "'''At T = 0K\n",
+      "(Ev+0.5)=(Ec+Ev)/2  -----(1)\n",
+      "\n",
+      "Let at temperature T, fermi level be shited by 10%\n",
+      "(Ev+06) = (Ec+Ev)/2 +(3kT*ln(4))/4  ----(2)\n",
+      "\n",
+      "Subtracting (1) from (2), we get the following expression'''\n",
+      "\n",
+      "T = (4*e/10)/(3*k*log(4))\n",
+      "\n",
+      "#Result\n",
+      "print \"Temperature =\",round(T,2),\"K\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Temperature = 1116.52 K\n"
+       ]
+      }
+     ],
+     "prompt_number": 11
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 9.11, Page number 9.17"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "Na = 5*10**23    #no. of atoms of boron\n",
+      "Nd = 3*10**23    #no. of atoms of arsenic\n",
+      "ni = 2*10**16    #intrinsic charge carriers(/m^3)\n",
+      "\n",
+      "#Calculations\n",
+      "p = (2*(Na-Nd))/2  #hole concentration(/m^3)\n",
+      "n = ni**2/p        #electron concentration(/m^3)\n",
+      "\n",
+      "#Result\n",
+      "print \"Hole concentration =\",round((p/1E+23),2),\"*10^23 per m^3\"\n",
+      "print \"Electron concentration =\",round((n/1E+9),2),\"*10^9 per m^3\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Hole concentration = 2.0 *10^23 per m^3\n",
+        "Electron concentration = 2.0 *10^9 per m^3\n"
+       ]
+      }
+     ],
+     "prompt_number": 12
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 9.12, Page number 9.18"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "ue = 0.13            #electron mobility(m^2/V-s)\n",
+      "uh = 0.05            #hole mobility(m^2/V-s)\n",
+      "e = 1.602*10**-19    #charge on electron(C)\n",
+      "ni = 1.5*10**16      #intrinsic charge carriers(/m^3) \n",
+      "\n",
+      "\n",
+      "#Calculations\n",
+      "#Part a\n",
+      "sigma = ni*e*(ue+uh)  #conductivity(1/ohm-m)\n",
+      "\n",
+      "#Part b\n",
+      "w = 28.1                  #atomic weight of Si\n",
+      "den = 2.33*10**3          #density of Si(kg/m^3)\n",
+      "n = (den*6.02*10**26)/w   #no. of atoms of silicon\n",
+      "#Since one donor type impurity atom is added in 10^8 Si atoms, \n",
+      "Nd = n/10**8\n",
+      "p = ni**2/Nd\n",
+      "sigma_ex = Nd*e*ue        #(per ohm-m)\n",
+      "\n",
+      "#Part c\n",
+      "Na = Nd         #Since one acceptor type impurity atom is added in 10^8 Si atoms\n",
+      "n2 = ni**2/Na\n",
+      "sigma_ax = Na*e*uh         #(per ohm-m)\n",
+      "\n",
+      "#Results\n",
+      "print \"a)Conductivity =\",round((sigma/1E-3),3),\"*10^-3 per ohm-m\"\n",
+      "print \"b)Conductivity if donor type impurity is added =\",round(sigma_ex,2),\"per ohm-m\"\n",
+      "print \"c)Conductivity if acceptor type impurity is added =\",round(sigma_ax,2),\"per ohm-m\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "a)Conductivity = 0.433 *10^-3 per ohm-m\n",
+        "b)Conductivity if donor type impurity is added = 10.4 per ohm-m\n",
+        "c)Conductivity if acceptor type impurity is added = 4.0 per ohm-m\n"
+       ]
+      }
+     ],
+     "prompt_number": 13
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 9.13, Page number 9.20"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "from math import log\n",
+      "\n",
+      "#Variable declaration\n",
+      "ue = 0.135            #electron mobility(m^2/V-s)\n",
+      "uh = 0.048            #hole mobility(m^2/V-s)\n",
+      "e = 1.602*10**-19     #charge on electron(C)\n",
+      "ni = 1.5*10**16       #intrinsic charge carriers(atoms/m^3)\n",
+      "k = 1.38*10**-23      #Boltzman constant(J/K)\n",
+      "T = 300               #assumption - Temperature(K)\n",
+      "Nd = 10**23           #doping concentration(atoms/m^3)\n",
+      "\n",
+      "#Calculations\n",
+      "sigma = ni*e*(ue+uh)  #conductivity of intrinsic Si\n",
+      "\n",
+      "p = ni**2/Nd          #hole concentration\n",
+      "\n",
+      "sigma_ex = Nd*e*ue    #conductivity at equilibrium\n",
+      "F = (3*k*T)/(4*e)*log(ue/uh)  #position of Fermi level\n",
+      "\n",
+      "#Results\n",
+      "print \"Conductivity of intrinsic Si is\",round((sigma/1E-3),4),\"*10^-3 per ohm-m\"\n",
+      "print \"Hole concentration at equilibrium is\",round((Nd/1E+23)),\"*10^23 per m^3\"\n",
+      "print \"Conductivity at equilibrium is\",round((sigma_ex/1E+3),2),\"*10^3 per m^3\"\n",
+      "print \"Fermi level will be\",round(F,2),\"eV above intrinsic level\" "
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Conductivity of intrinsic Si is 0.4397 *10^-3 per ohm-m\n",
+        "Hole concentration at equilibrium is 1.0 *10^23 per m^3\n",
+        "Conductivity at equilibrium is 2.16 *10^3 per m^3\n",
+        "Fermi level will be 0.02 eV above intrinsic level\n"
+       ]
+      }
+     ],
+     "prompt_number": 14
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 9.14, Page number 9.35"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "ue = 0.19             #electron mobility(m^2/V-s)\n",
+      "e = 1.602*10**-19     #charge on electron(C)\n",
+      "T = 300               #Temperature(K)\n",
+      "\n",
+      "#Calculation\n",
+      "Dn = (ue*k*T)/e\n",
+      "\n",
+      "#Result\n",
+      "print \"Diffusion co-efficient =\",round((Dn/1E-4),2),\"*10^-4 m^2/s\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Diffusion co-efficient = 49.1 *10^-4 m^2/s\n"
+       ]
+      }
+     ],
+     "prompt_number": 15
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 9.15, Page number 9.45"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "Rh = 3.66*10**-4   #Hall coefficient\n",
+      "I = 10**-2         #current(A)\n",
+      "B = 0.5            #magnetic field intensity(wb/m^2)\n",
+      "t = 1.*10**-3      #thickness of plate(m)\n",
+      "\n",
+      "#Calculations\n",
+      "Vh = (Rh*I*B)/t\n",
+      "\n",
+      "#Result\n",
+      "print \"Hall coefficient =\",(Vh/1E-3),\"mV\"\n"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Hall coefficient = 1.83 mV\n"
+       ]
+      }
+     ],
+     "prompt_number": 6
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 9.16, Page number 9.46"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "Vy = 37*10**-6      #voltage(V)\n",
+      "t = 10**-3          #thickness of crystal(m)\n",
+      "Bz = 0.5            #magnetic field intensity(Wb/m^2)\n",
+      "Ix = 20*10**-3      #current(A)\n",
+      "\n",
+      "#Calculations\n",
+      "Vh = (Vy*t)/(Ix*Bz)\n",
+      "\n",
+      "#Result\n",
+      "print \"Hall coefficient =\",(Vh/1E-6),\"*10^-6 m^3/C\"\n"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Hall coefficient = 3.7 *10^-6 m^3/C\n"
+       ]
+      }
+     ],
+     "prompt_number": 7
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 9.17, Page number 9.46"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "Rh = 7.35*10**-5   #Hall coefficient(m^3/C)\n",
+      "e = 1.6*10**-19    #charge on electron(C)\n",
+      "sigma = 200        #conductivity(/ohm-m)\n",
+      "n = 8.023*10**22   #Avogadro's number\n",
+      "\n",
+      "#Calculations\n",
+      "n = 1/(Rh*e)\n",
+      "\n",
+      "u = sigma/(n*e)\n",
+      "\n",
+      "#Results\n",
+      "print \"Density =\",round((n/1E+22),3),\"*10^22 m^3\"\n",
+      "print \"Conductivity =\",round((u/1E-3),2),\"*10^-3 m^2/V-s\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "Density = 8.503 *10^22 m^3\n",
+        "Conductivity = 14.7 *10^-3 m^2/V-s\n"
+       ]
+      }
+     ],
+     "prompt_number": 8
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 9.18, Page number 9.47"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "I = 50           #current(A)\n",
+      "B = 1.5          #magnetic field intensity(T)\n",
+      "n = 8.4*10**28   #free electron concentration in copper(electron/m^3)\n",
+      "t = 0.5*10**-2   #thickness of slab(m)\n",
+      "\n",
+      "#Calculation\n",
+      "Vh = (I*B)/(n*e*t)\n",
+      "\n",
+      "#Result\n",
+      "print \"The magnitude of Hall voltage is\",round((Vh/1E-6),3),\"*10^-6 V\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "The magnitude of Hall voltage is 1.116 *10^-6 V\n"
+       ]
+      }
+     ],
+     "prompt_number": 9
+    },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Example 9.19, Page number 9.48"
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "\n",
+      "#Variable declaration\n",
+      "Rh = 3.66*10**-4   #Hall coefficient(m^3/C)\n",
+      "e = 1.6*10**-19    #charge on electron(C)\n",
+      "Pn = 8.93*10**-3   #resistivity(ohm-m)\n",
+      "\n",
+      "#Calculation\n",
+      "n = 1/(Rh*e)\n",
+      "\n",
+      "ue = Rh/Pn\n",
+      "\n",
+      "#Result\n",
+      "print \"n =\",round((n/1E+22),3),\"*10^22/m^3\"\n",
+      "print \"u =\",round(ue,3),\"m^2/V-s\""
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "n = 1.708 *10^22/m^3\n",
+        "u = 0.041 m^2/V-s\n"
+       ]
+      }
+     ],
+     "prompt_number": 10
+    }
+   ],
+   "metadata": {}
+  }
+ ]
+}
\ No newline at end of file
diff --git a/Solid_state_physics/README.txt b/Solid_state_physics/README.txt
new file mode 100755
index 00000000..604bb793
--- /dev/null
+++ b/Solid_state_physics/README.txt
@@ -0,0 +1,10 @@
+Contributed By: Muktesh Chaudhary
+Course: be
+College/Institute/Organization: Anglo Eastern ship management india Pvt. Ltd
+Department/Designation: Electrical & Electronics Officer
+Book Title: Solid state physics
+Author: P. K. Palanisamy
+Publisher: Scitech Publication (India) Pvt. Ltd., Chennai
+Year of publication: 2011
+Isbn: 9788188429279
+Edition: 1st
\ No newline at end of file
diff --git a/Solid_state_physics/screenshots/forbidden.png b/Solid_state_physics/screenshots/forbidden.png
new file mode 100755
index 00000000..7d37c14d
--- /dev/null
+++ b/Solid_state_physics/screenshots/forbidden.png
diff --git a/Solid_state_physics/screenshots/interatomicspacing.png b/Solid_state_physics/screenshots/interatomicspacing.png
new file mode 100755
index 00000000..ecce2e8b
--- /dev/null
+++ b/Solid_state_physics/screenshots/interatomicspacing.png
diff --git a/Solid_state_physics/screenshots/magneticmoment.png b/Solid_state_physics/screenshots/magneticmoment.png
new file mode 100755
index 00000000..a7a3e706
--- /dev/null
+++ b/Solid_state_physics/screenshots/magneticmoment.png