Question

The zone plate behaves like a ____________

(a) Concave Lens with multiple foci

(b) Convex Lens with multiple foci

(c) Convex Lens with single foci

(d) Concave Lens with single foci

This question was addressed to me in an interview for internship.

I want to ask this question from Fresnel Diffraction in division Optics of Engineering Physics II

Answer 1

Right choice is (b) Convex Lens with multiple foci

Easy explanation: In a zone plate, a much brighter image of an object is obtained at the screen, which shows the converging action of a zone plate. Also, it’s equation resembles that of a lens. Thus, the zone plate behaves like a convex lens with multiple foci.