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{
"metadata": {
"name": ""
},
"nbformat": 3,
"nbformat_minor": 0,
"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"Chapter 10:The Solid state"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 10.1,Page no:342"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Variable declaration \n",
"import math\n",
"Ro= 0.281 #equilibrium distance between ions, nm\n",
"alpha= 1.748 #Madelung constant\n",
"n= 9 #exponent, from observed compressibilities of NaCl\n",
"e= 1.6*(10**(-19)) #charge of an electron, C\n",
"Po= 8.85*(10**(-12)) #Permittivity of free space, F/m\n",
"\n",
"#Calculation\n",
"K=1.0/(4*(math.pi)*Po) #constant, N.m**2/C**2\n",
"Uo= -(K*alpha*(e**2)*(1.0-(1.0/n)))/(Ro*(10**(-9))) #Potential energy per ion pair, J\n",
"Uo= Uo/e #converting to eV\n",
"E1= 5.14 #Ionisation energy for Na, eV\n",
"E2= -3.61 #electron affinity of Cl, eV\n",
"E= E1+E2 #Electron transfer energy, eV\n",
"Ecohesive = (Uo +E) #per electron pair, eV\n",
"Ecohesive= Ecohesive/2.0 #for each ion, eV\n",
"\n",
"#Result\n",
"print\"The cohesive energy in NaCl is: \",round(Ecohesive,2),\"eV\"\n",
"print\"\\nWhich is not far from experimental value of -3.28 eV\"\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The cohesive energy in NaCl is: -3.21 eV\n",
"\n",
"Which is not far from experimental value of -3.28 eV\n"
]
}
],
"prompt_number": 2
},
{
"cell_type": "heading",
"level": 3,
"metadata": {},
"source": [
"Example 10.2,Page no:350"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"#Variable declaration \n",
"A= 1.0 #cross-sectional area of wire, mm**2\n",
"I= 1.0 #current in wire, A\n",
"n= 8.5*(10**28) # electrons/m**3\n",
"e= 1.6*(10**(-19)) #charge of an electron, C\n",
"\n",
"#Calculation\n",
"Vdrift= I/(n*(A*(10**(-6)))*e) #m/s\n",
"\n",
"#Result\n",
"print\"The drift velocity of electrons in the copper wire is:%.2g\"%Vdrift,\"m/s\"\n",
"print\"\\nNOTE:Calculation mistake in book.Wrongly written as 7.4*10^-4\"\n",
" \n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The drift velocity of electrons in the copper wire is:7.4e-05 m/s\n",
"\n",
"NOTE:Calculation mistake in book.Wrongly written as 7.4*10^-4\n"
]
}
],
"prompt_number": 3
},
{
"cell_type": "heading",
"level": 3,
"metadata": {},
"source": [
"Example 10.3,Page no:353"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Variable declaration \n",
"n= 8.48*(10**28) #free electron density, m**(-3)\n",
"Vfermi= 1.57*(10**6) #Fermi Velocity, m/s\n",
"rho= 1.72*(10**(-8)) #resistivity, ohm\n",
"e= 1.6*(10**(-19)) #charge of an electron, C\n",
"Me= 9.1*(10**(-31)) #mass of electron, kg\n",
"\n",
"#Calculation\n",
"lamda= Me*Vfermi/(n*(e**2)*rho) #m\n",
"lamda= lamda*(10**9) #converting to nm\n",
"\n",
"#Result\n",
"print\"The mean free path is:\",round(lamda,1),\"nm\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The mean free path is: 38.3 nm\n"
]
}
],
"prompt_number": 4
}
],
"metadata": {}
}
]
}
|
