Question

If a drop of water is introduced between the glass plate and a convex lens in a Newton's ring system, the ring system
A. expands
B. contracts
C. remains same
D. First expands then contracts

Answer 1

Hint : An equal light emission light is reflected towards the focal point L. Consider a light emission light strikes typically on the upper surface of the air film.The pillar gets halfway reflected and incompletely refracted.

Complete Step By Step Answer:
At the point when a plano-arched focal point with its raised surface is put on a plane glass plate, an air film of progressively expanding thickness is framed between the focal point and the glass plate. The thickness of the air film is very nearly zero at the purpose of contact O and step by step increments as one continues towards the outskirts of the focal point.
In the event that monochromatic light is permitted to fall regularly on the focal point, and the film is seen in mirrored light, substitute brilliant and dull concentric rings are seen around the purpose of contact. These rings were first found by Sir Isaac Newton, consequently named as Newton's Rings. On the off chance that it is seen with the white light, hued borders are gotten.
The test course of action of the Newton's Ring apparatus the refracted shaft noticeable all around film is additionally reflected part of the way at the lower surface of the film. The two reflected beams, for example created at the upper and lower surface of the film, are intelligible and meddle productively or ruinously.
Hence correct answer is option is (B).

Note :
The distance across of Newton's rings is conversely relative to refractive record. So when a drop of water is presented between the glass plate and Plano-raised focal point in Newton's rings, the ring framework contacts.