d sinθ = nλ ; n = 1,2,3 for bright band

Mumbai university > FE > SEM 2 > Applied Physics II

Marks: 5M

Year: Dec 2014,May 2014

Consider a parallel beam of light incidented upon grating with grating element (d) and diffracted through angle (θ)

The path difference between adjacent amplitude vectors is :-

BC = (a + b)sin θ = d sin θ

For constructive interference

BC = nλ

d sinθ = nλ (n=1,2,3,...)

Hence proved