A spherical mirror forms an image of magnification3. The object distance, if focal length of mirror is 24cm, may be

Options

A. 32cm, 24cm
B. 32cm, 16cm
C. 32cm only
D. 16cm only

Answer

b.

Explanation

`m=(f)/(f-u)`
`3=(-24)/(-24-u)`
or `-24-u=-8 or u+24=8`
or `u=(8-24)cm=-16cm`
If `m=-3,` then
`-3=(-24)/(-24-u)`
`u+24=-8`
or `u=-32cm`.