Question

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

Answer 1

image is formed at focus because incident rays are parallel to principal axis..
so focal lenth(distance of focus from pole) is 12 cm..
radius of curvature is double of focal length.
$r = 2f$
so radius of curvature is 24 cm.

Answer 2

24cm is radius of curvature of mirror