Question

White light is used to illuminate the two slits in Young’s double slit experiment. The separation between the slits is b and the screen is at a distance d  (>b ) from the slits. At a point on the screen directly in front of one of the slits, certain wavelengths are missing. Some of these missing wavelengths are 

(a)  λ = b²/d

(b)  λ = 2b²/d

(c)  λ = b²/3d

(d)  λ = 2b/3d

Answer 1

Correct option  (a) and (c) 

Explanation:

Those wavelengths are missing for which path difference

Thus correct answers are (a) and (c).

Comments

How we get to know that it's a distructive interfarance ?.