The focal length of a plano-convex lens is `f` and its refractive index is 1.5 it is kept over a
Channel: Doubtnut
Date: 02/11/2021

The focal length of a plano-convex lens is `f` and its refractive index is 1.5 it is kept over a plane galss plate with its curved surface touching the glass plate. The gap between the lens and the glass plate is filled by a liquid. As a result the effective focal length of the combination becomes `2f`. Then the refractive index of the liquid is