If f is focal length and u is object distance for spherical mirror, then lateral magnification m = ......

Options

A. `(f)/(u-f)`
B. `(f)/(u+f)`
C. `(f)/(f-u)`
D. `(f-u)/(f)`

Answer

C

Explanation

For spherical mirror,
`1/f=1/u+1/v implies 1/f-1/u=1/v` < br> `therefore (u-f)/(fu)=1/v`
`therefore(u-f)/(f)=u/v`
`-v/u=-((f)/(u-f))therefore m=(f)/(f-u)`