Question

A convex mirror of focal length $f$ produces an image $\frac{1}{n}$th of the size of the object. The distance of the object from the mirror is:

• A. $(n-1)f$
• B. $\frac{f}{n}$
• C. $(n+1)f$
• D. $nf$

Answer 1

The correct option is C $(n+1)f$

$m=\frac{1}{n}=\frac{-v}{(-u)}\Rightarrow v=\frac{u}{n}$
As $\frac{1}{v}+\frac{1}{u}=\frac{1}{f}\therefore \frac{n}{u}+\frac{1}{u}=\frac{1}{f}$
$u=(n+1)f$