Question

the radius of curvature of a concave mirror is 30 cm. find the focal length of the mirror

Answer 1

Focal length is half the radius of the mirror.

Explanation:

So

f

=

30

/

2

=

15

c

m

With a spherical mirror this is not the focal length, as rays do not converge in one point, depending on their distance from the optical axis. But for small mirrors this will do.