A parallel beam of light of wavelength 600 nm is incident normally on a slit of width 0.2 mm. If the resulting diffraction pattern is observed on a screen 1 m away, find the distance of
(i) First minimum, and
(ii) Second maximum, from the central maximum. 

Asked by suman.sh01 | 21st May, 2022, 11:09: AM

Expert Answer:

First minimum occurs at angular position θ = λ /a
 
where λ is wavelength of light used , a is slit width
 
First minimum occurs at angular position θ = ( 600 × 10-9 ) / ( 2 × 10-4 )
 
First minimum occurs at angular position θ =  3 × 10-3 rad
 
Let D be the distance between slit and screen.
 
Distance of first minimum from central maximum = ( D θ ) = 1 × 3 × 10-3 m = 3 mm
 
--------------------------------------------
First maximum occurs at angular position θ = (3/2) (λ /a)
 
 
First maximum occurs at angular position θ = (3/2) ( 600 × 10-9 ) / ( 2 × 10-4 )
 
First maximum occurs at angular position θ  4.5 × 10-3 rad
 
Distance of first maximum from central maximum  = ( D θ ) = 1 × 4.5 × 10-3 m = 4.5 mm
 

Answered by Thiyagarajan K | 21st May, 2022, 04:43: PM