When a pin is moved along the principal axis of a small concave mirror, the image position coincides with the object at a point 0.5 m from the mirror refer figure . If the mirror is placed at a depth of 0.2 m in a transparent liquid, the same phenomenon occurs when the pin is placed 0.4 m from the mirror . The refractive index of the liquid is :-

Options

A. `6//5`
B. `5//4`
C. `4//3`
D. `3//2`

Answer

D

Explanation

Image position coincides with the object when an object is placed on centre of curvature i.e. R= 0.5m when transparent liquid is filled then phenomenon occurs when the pin placed 0.4 m from mirror i.e. effective distance must be 0.5 again
`0.2 + mu 0.2 = 0.5` , `mu= 3//2`