A hollow glass sphere of refractive index has a small mark on its interior surface
PHYSICS · Subjective · CBSE · Physics · Ray Optics and Optical Instruments · Ray Optics and Optical Instruments
Problem
A hollow glass sphere of refractive index μ has a small mark on its interior surface. It is observed from outside the sphere on the side opposite the centre. The inner cavity is concentric with the external surface, and the glass thickness everywhere equals the inner radius. Prove that the mark appears nearer than it really is by a distance 3μ−1(μ−1)r, where r is the inner radius.