Chapter 24:Interference and Diffraction

Ex24.1:pg-1130

  #Example 24_1
import math 
  
  #To find the angle at which the reinforcement line occurs
n=2      #units in constant
lamda=0.7         #units in cm
d=2          #units in cm
theta2=math.asin((n*lamda)/d)*180/math.pi       #Units in degrees
print "The angle at which the reinforcement line occurs is theta2=",round(theta2)," degrees"

The angle at which the reinforcement line occurs is theta2= 44.0  degrees

Ex24.2:pg-1131

  #Example 24_2
import math 
  
  #To find by how much does thickness of air gap increases
lamda=589           #units in nm
gap=round(lamda/2)          #units in nm
print "The thickness of air gap increases by=",round(gap)," nm"

The thickness of air gap increases by= 294.0  nm

Ex24.3:pg-1132

  #Example 24_3
import math 
  
  #To find the thickness that should be coated for minimum reflection
lamda=550         #units in nm
n=1.38            #units in constant
L=(lamda/2)/(2*n)         #units in nm
print "The thickness that should be coated for minimum reflection is L=",round(L,1)," nm"

The thickness that should be coated for minimum reflection is L= 99.6  nm

Ex24.4:pg-1133

  #Example 24_4

import math 
  
#To find out the angle at which the line appears
line=5.89*10**-7          #Units in meters
noline=1/10.0**6         #units in Lines per meter
theta1=math.sin(line/noline)*180/math.pi      #units in degrees
#For second order
theta2=math.sin(2*line/noline)*180/math.pi      #units in degrees
print "For the first order theta1=",round(theta1)," degrees\nFor the second order theta2=",round(theta2)," degrees"
sinevalue=2*line/noline        #units in radians
print "\n As it is impossible for the sine of angle that is=",round(sinevalue,2)," radians to be greater that unity this second order and higher order images doesnot exist"

For the first order theta1= 32.0  degrees
For the second order theta2= 53.0  degrees

 As it is impossible for the sine of angle that is= 1.18  radians to be greater that unity this second order and higher order images doesnot exist