A concave mirror is placed at the bottom of an empty tank with face upwards and axis
Channel: Doubtnut
Date: 2020-08-16

A concave mirror is placed at the bottom of an empty tank with face upwards and axis vertical. When sunlight falls normally on the mirror, it is focussed at distance of `32cm` from the mirror. If the tank filled with water `(mu=4//3)` up to a height of `20cm`, then the sunlight will now get focussed at