The separation between the screen and a concave mirror is 2 r . An isotropic point source of light
Channel: Doubtnut
Date: 2020-08-23

The separation between the screen and a concave mirror is 2 r . An isotropic point source of light is placed exactly midway between the mirror and the point source. Mirror has a radius of curvature r and reflects 100% of the incident light. Then the ratio of illuminances on the screen with and without the mirror is