Question

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
A. `16cm` above water level
B. `9cm` above water level
C. `24cm` below water level
D. `9cm` below water level

Answer 1

Correct Answer - B

`AI=12cm`, `mu=4//3`
`AI=mu(AO)`
`12=4/3(AO)impliesAO=9cm`