Question

A thin equiconvex lens of glass of refractive index 1.5
whose surfaces have a radius of curvature of 24 cm is
placed on a horizontal plane mirror. When the space
between the lens and mirror is filled with a liquid, a pin
held 40 cm vertically above the lens is found to coincide
with its own image. Calculate the refractive index of the
liquid.​

Answer 1

Explanation:

If equiconvex lens of glass has refractive index μ=1.5 and radius of curvature R=20cm then find refractive index of the liquid. Solution : If an object has to coincide with its image, then the ray have to retrace its path, hence, it is concluded that object is at the focus of the combination.