Question

a slit of width a is illuminated by white light the first minimum for red light will fall at theta is equal to 30 degree when a will be..(lemda=6500A)​

Answer 1

First minimum (dark fringe) at  a sin θ = n λ  ,    where n = 1

            so  sin θ = λ / a

     a = 6000 * 10⁻¹⁰ m * 2 = 1.2 μ meter 

first maximum (after central bright region and first dark fringe) falls at

        sinθ = (n+1/2) λ/a ,        where  n = 1

         a = 3/2 * λ / sinθ = 1.8 μm 

Answer 2

Explanation:

this is My q.pls tell me it's ans.