Question

A man has a shaving mirror of focal length $0.2m$. How far should be held from his face in order to give an image of two fold magnification ?

Answer 1

Focal length of the Mirror $f=-0.2m$

Magnification $m=2$

We know that,

$m=\frac{-v}{u}$

$v=-2u$

Now, using the Mirror's Formula, (Concave Mirror)

$\frac{1}{f}=\frac{1}{v}+\frac{1}{u}$

$\frac{1}{-0.2}=\frac{1}{-2u}+\frac{1}{u}$

$\frac{1}{2u}=\frac{1}{-0.2}$

$u=-0.1m$

Hence, the man is standing at the distance of $0.1m$ from the saving mirror.