Question

A point object is placed 30 cm from convex lens of focal length 20 cm. A convex mirror of radius of curvature 12 cm is placed at distance $6\times ncm$ away from lens on other side. If image coincides with object n is

Answer 1

$\frac{1}{f}=\frac{1}{v}-\frac{1}{u}\Rightarrow \frac{1}{20}=\frac{1}{v}+\frac{1}{30}$
$\Rightarrow v=60cm$

$6n+12=60\Rightarrow n=8$