# Chapter 4:Imperfections in solids¶

### Example 4.1 Page No: 82¶

In [13]:
den=8.4*10**6        #Density of Copper
A=63.5              #Atomic weight of Copper

N=Na*den/A
Qv=0.9                 #Activation energy in eV
k=8.62*10**-5          # Boltzmann Constatnt in eV/K
T=1000.0+273.0         #Temperature in K
Nv=N*exp(-Qv/(k*T))

print"No.of vacancies are ",round(Nv,-24),"/m**3"
No.of vacancies are  2.2e+25 /m**3

### Example 4.3 Page No: 88¶

In [9]:
C_Al=97.0       #Aluminium wt%
C_Cu=3.0        #Copper wt%
A_Al=26.98      #Atomic wt of Aluminium
A_Cu=63.55      #Atomic wt of Copper

CAl=(C_Al*A_Cu)/(C_Al*A_Cu+C_Cu*A_Al)
CCu=(C_Cu*A_Al)/(C_Al*A_Cu+C_Cu*A_Al)

print"Atomic % of Al is ",round(CAl*100,1),"%"
print"Atomic % of Cu is ",round(CCu*100,1),"%"
Atomic % of Al is  98.7 %
Atomic % of Cu is  1.3 %

### Example 4.4 Page No: 103¶

In [12]:
N=45.0           #No. of grains per square inch

n=(math.log(N)/math.log(2))+1

M=85.0
Nm=(100/M)**2*2**(n-1)

print"Grain size no. is ",round(n,1)
print"No. of grains per inch square are ",round(Nm,1)
Grain size no. is  6.5
No. of grains per inch square are  62.3
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