A zone plate is a diffracting screen which behaves like a
(A) convex lens
(B) concave lens
(C) convex mirror
(D) concave mirror
The correct answer is: (A) convex lens
Explanation:
A zone plate is an optical device made up of alternating transparent and opaque concentric rings, designed based on the principle of diffraction.
- It focuses light through constructive interference of diffracted waves.
- It produces a real focus just like a convex lens, even though it has no curved surfaces.
Key Point:
- While a convex lens focuses light through refraction, a zone plate does so through diffraction.
- But in terms of function, both produce similar focusing effects.
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