Question

Sunlight is incident on a concave mirror, parallel to its principal axis. The image is formed at a distance of 12 cm from the pole. Find the radius of curvature of the mirror.

Answer 1

As the rays from the sun are parallel to the principal axis, they form the image at the focus. Thus the local length of the mirror is 12 cm. The radius of curvature will be twice the focal length, i.e. 24 cm.

We can solve it

Here rays are parallel So $u=\infty$

$v=12cm$

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

$f=12cm$

Radius of curvature $R=2f=24$ cm