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);
```

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);
```

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"
```