# Chapter 11:Solid State Physics¶

## Example 11.1, Page 346¶

In [1]:
#initiation of variable
c=769.0*10**3; Na=6.023*10**23; JeV=1.6*10**-19; #various constants and given values

#calculation
Be=c/(Na*JeV);        #Binding energy of an ion pair in the lattice

#result
print"The experimental value was found out to be in eV.",round(Be,5);

#partb
n=9.0;a=1.7476; R=0.281; k= 1.44;     #Given values and consstants
Bc=k*a*(1-(1/n))/R;                  #ionic binding energy experimentally

#result
print"The calculated value of the binding energy in eV.is",round(Bc,4);

The experimental value was found out to be in eV. 7.97983
The calculated value of the binding energy in eV.is 7.9606


## Example 11.2, Page 350¶

In [2]:
#initiation of variable
a=3.61;# amount of energy required to remove an electron from Cl- ion
b=-5.14 #amount of energy returned when an electron is added to Na+ ion\
c=7.98 #binding energy of NaCl atom

#calculation
E=a+b+c  #sum of all the energies
print"The net energy to be supplied in eV is",round(E,3);

The net energy to be supplied in eV is 6.45


## Example 11.3, Page 355¶

In [1]:
#initiation of variable
from math import exp,sqrt
Na=6.023*10**23; p=8.96*10**3; M=63.5*10**-3;   #Na=avagadro's number,p=density,M=molar mass

#calculation
n= p*Na/M;                                   #density of charge carriers

#result'
print"The density of charge carriers in copper in atoms/m3 is %.1e" %round(n,3);

s=5.88*10**7;m=9.11*10**-31;e=1.6*10**-19;    #charge & mass of an electron,resistance per unit length
t= s*m/(n*e**2);                            #average time between collisions

#result
print "The average time between collisions of conducting electrons in sec.is %.1e" %t

#partb
Ef=7.03*1.6*10**-19;           #converting given enrgy to J

#calculation
Vf=sqrt(2*Ef/m);               #fermi velocity
l=Vf*t;                      #mean free path

#result
print "The average mean free path is",l,"m =",round(l*10**9,3)," nm"

The density of charge carriers in copper in atoms/m3 is 8.5e+28
The average time between collisions of conducting electrons in sec.is 2.5e-14
The average mean free path is 3.8690296096e-08 m = 38.69  nm