In [4]:

```
#importing modules
import math
from __future__ import division
#Variable declaration
n=125; #number of fingers cross the field of view
d=0.04*10**-3; #distance of one of mirror moved(m)
#Calculation
w=2*d/n; #wavelength of light used(m)
#Result
print "The wavelength of light used is",int(w*10**9),"nm"
```

In [6]:

```
#importing modules
import math
from __future__ import division
#Variable declaration
Ri=1.5; #refractive index of thin film of glass
n=30; #number of fringes of sodium light is observed across the field of view
t=0.018*10**-3; #thickness of glass film(m)
#Calculation
w=2*(Ri-1)*t/n; #wavelength of the light used(m)
#Result
print "The wavelength of light used is",w*10**9,"nm"
```

In [9]:

```
#importing modules
import math
from __future__ import division
#Variable declaration
n=200; #number of fringes cross the field of view
d=0.0589*10**-3; #distance of mirror displaced(m)
#Calculation
w=2*d/n; #wavelength of the monochromatic source used(m)
#Result
print "The wavelength of the monochromatic source used is",w*10**9,"nm"
```

In [11]:

```
#importing modules
import math
from __future__ import division
#Variable declaration
x=1.55; #refractive index of transparent film of glass
w=480*10**-9; #wavelength of light(m)
n=450; #number of fringes to sweep across the field
#Calculation
t=n*w/(2*(x-1)); #thickness of the film(m)
#Result
print "The thickness of the film is",round(t*10**4,4),"*10**-4 m"
```

In [12]:

```
#importing modules
import math
from __future__ import division
#Variable declaration
t=0.004*10**-2; #thickness of transparent sheet(m)
d=0.0027*10**-2; #distance of mirror displaced(m)
#Calculation
X=(d/t)+1; #refractive index of the material
#Result
print "The refractive index of material is",X
```

In [14]:

```
#importing modules
import math
from __future__ import division
#Variable declaration
d=0.03205*10**-3; #distance of movable mirror displaced(m)
w=580.9*10**-9; #wavelength of light(m)
#Calculation
n=2*d/w; #number of fringes shifted across the cross wire of eye piece of the telescope
#Result
print "The number of fringes shifted across the cross wire of eye piece of the telescope is",int(n)
```

In [17]:

```
#importing modules
import math
from __future__ import division
#Variable declaration
w=5893*10**-10; #wavelength of sodium light(m)
Re=1.5532; #Refractive index of quartz for e ray
Ro=1.5332; #Refractive index of quartz for o ray
#Calculation
t=w/(4*(Re-Ro)); #thickness of a quarter wave plate of quartz for sodium light(m)
#Result
print "The thickness of a quarter wave plate of quartz for sodium light is",t*10**6,"micro m"
```

In [19]:

```
#importing modules
import math
from __future__ import division
#Variable declaration
w=6000*10**-10; #wavelength(m)
Re=1.54; #Refractive index of double refracting crystal for e ray
Ro=1.65; #Refractive index of double refracting crystal for o ray
#Calculation
t=w/(2*(Ro-Re)); #thickness of a double refracting crystal required at w/2(m)
#Result
print "The thickness of a double refracting crystal required at w/2 is",round(t*10**6,3),"micro m"
```

In [21]:

```
#importing modules
import math
from __future__ import division
#Variable declaration
w=5*10**-7; #wavelength(m)
Re=1.5573; #Refractive index for e ray when the emergent beam will be plane polarised
Ro=1.5442; #Refractive index for o ray when the emergent beam will be plane polarised
#Calculation
t=w/(4*(Re-Ro)); #least thickness of a plate(m)
#Result
print "The least thickness of a plate when the emergent beam will be plane polarised is",round(t*10**6,2),"micro m"
```

In [24]:

```
#importing modules
import math
from __future__ import division
#Variable declaration
w=5893*10**-10; #wavelength of sodium light(m)
Ro=1.658; #Refractive index of calcite for o ray
Re=1.486; #Refractive index of calcite for e ray
#Calculation
t=w/(2*(Ro-Re)); #thickness of the quarter wave plate for calcite(m)
#Result
print "The thickness of the quarter wave plate for calcite is",round(t*10**6,3),"*10**-6 m"
print "answer given in the book is wrong"
```

In [26]:

```
#importing modules
import math
from __future__ import division
#Variable declaration
t=30*10**-6; #thickness of wave plate(m)
Ro=1.55; #Refractive index of wave plate for o ray
Re=1.54; #Refractive index of wave plate for e ray
#Calculation
w=2*t*(Ro-Re); #wavelength for which it can act as a half wave plate(m)
#Result
print "The wavelength for which it can act as a half wave plate is",w*10**9,"*10**-9 m"
```

In [28]:

```
#importing modules
import math
from __future__ import division
#Variable declaration
w=546.1*10**-9; #wavelength of light(m)
Re=1.592; #Refractive index of mica for e ray
Ro=1.586; #Refractive index of mica for o ray
#Calculation
t=w/(2*(Re-Ro)); #thickness of a mica sheet(m)
#Result
print "The thickness of a mica sheet required for making a half wave plate for a light is",round(t*10**5,4),"*10**-5 m"
```