7: Interference

Example number 7.1, Page number 16

In [4]:
#importing modules
import math
from __future__ import division

#Variable declaration
theta=40;    #angle of wedge(s)
beta=0.125*10**-2;   #fringe width(m)

#Calculation
lamda=2*beta*theta*(math.pi/180)*(1/60)*(1/60);    #wavelength of light(m)

#Result
print "wavelength of light is",int(lamda*10**10),"angstrom"

wavelength of light is 4848 angstrom

Example number 7.3, Page number 17

In [6]:
#importing modules
import math
from __future__ import division

#Variable declaration
n=100;    #number of fringes
d=0.03*10**-3;    #distance moved(m)

#Calculation
lamda=2*d/n;   #wavelength of light(m)

#Result
print "wavelength of light is",lamda*10**10,"angstrom"

wavelength of light is 6000.0 angstrom

Example number 7.4, Page number 17

In [13]:
#importing modules
import math
from __future__ import division

#Variable declaration
lamda1=5896*10**-10;    #wavelength of D1 line(m)
lamda2=5890*10**-10;    #wavelength of D2 line(m)

#Calculation
d=lamda1*lamda2/(2*(lamda1-lamda2));    #distance the mirror has to be moved(m)

#Result
print "distance the mirror has to be moved is",round(d*10**3,4),"mm"

distance the mirror has to be moved is 0.2894 mm

Example number 7.5, Page number 18

In [15]:
#importing modules
import math
from __future__ import division

#Variable declaration
mew=1.5;     #refractive index of plate
d=1.24;    #distance between dark fringes(mm)

#Calculation
t=d/(mew-1);    #thickness of glass plate(mm)

#Result
print "thickness of glass plate is",t,"mm"

thickness of glass plate is 2.48 mm