A narror parallel beam of light is incident  paraxially on a solid  transparent
Channel: Doubtnut
Date: 19/04/2020

A narror parallel beam of light is incident  paraxially on a solid  transparent  sphere  of radius `r` kept in air. What should  be the refreative  index if the beam is to be focusd  (a)  at the further  surface  of the sphere, (b) at the centre   of the sphere.