Physics 

Asked by ramdasiyogesh2001 | 12th Mar, 2021, 12:47: AM

Expert Answer:

We get diffraction from grating if the following condition is satisfied
 
( d sinθn ) = n λ
 
where d is line spacing , θn is nth order diffraction angle for light of wavelength λ and n is order of diffraction
 
For the given grating has 5000 lines per cm , then line spacing d = 10-2 / 5000 = 2 × 10-6 m
 
Wavelength of light used , λ = 6000 Ao
 
For first order diffraction, n = 1 ,   sinθ1 = λ/d  = ( 6000 × 10-10 ) / ( 2 × 10-6 ) = 0.3
 
For second order diffraction, n = 2 ,   sinθ2 = 2 λ/d  = ( 2 × 6000 × 10-10 ) / ( 2 × 10-6 ) = 0.6
 
For third order diffraction, n = 3 ,   sinθ3 = 3 λ/d  = ( 3 × 6000 × 10-10 ) / ( 2 × 10-6 ) = 0.9
 
For higher order , sinθn > 1 , which is not possible
 
we get maximum 3 order spectrum with the given gratings and wavelength used
 

Answered by Thiyagarajan K | 12th Mar, 2021, 04:23: PM