# Chapter 26 Diffraction of light¶

## Example 26.1 Page no 747¶

In :
#Given
a=0.5*10**-3                 #m
l=6000*10**-10
D=2

#Calculation
d=2*D*l/a

#Result
print"Distance between the two dark bands is",d*10**3,"mm"

Distance between the two dark bands is 4.8 mm


## Example 26.2 Page no 747¶

In :
#Given
l=5900*10**-10                   #m
a=11.8*10**-7

#Calculation
import math
a=l/a
A=math.asin(a)*180/3.14
A1=2*A

#Result
print"Angular position is",round(A1,0),"degree"

Angular position is 60.0 degree


## Example 26.3 Page no 747¶

In :
#Given
l=650*10**-9
a1=30                    #degree

#Calculation
a=l/math.sin(a1*3.14/180.0)
a2=3*l/math.sin(a1*3.14/180.0)

#Result
print"(a) Value of a when the 1st min. falls at 30 degree is",round(a*10**6,1)*10**-6,"m"
print"(b) Value of a when the 1st max. falls at 30 degree is",round(a2*10**6,2)*10**-6,"m"

(a) Value of a when the 1st min. falls at 30 degree is 1.3e-06 m
(b) Value of a when the 1st max. falls at 30 degree is 3.9e-06 m


## Example 26.4 Page no 747¶

In :
#Given
l=600.0*10**-9                   #m
a=2*10**-3

#Calculation
Z=a**2/l

#Result
print"Distance is",round(Z,2),"m"

Distance is 6.67 m


## Example 26.5 Page no 747¶

In :
#Given
l=5460*10**-10                         #m

#Calculation
D=1.22*l/d

#Result
print"Aperture of the objective of the telescope is",round(D,4),"m"

Aperture of the objective of the telescope is 0.1448 m


## Example 26.6 Page no 748¶

In :
#Given
lr=660

#Calculation
l1=2*lr/3.0

#Result
print"Value of lembda is",l1,"nm"

Value of lembda is 440.0 nm