Question

A 31 cm tall object is placed in front of a concave mirror with a radius of 34 cm. The distance of the object to the mirror is 93 cm. Calculate the focal length of the mirror.

Answer 1

Focal length is the distance between the center of a convex lens or a concave mirror and the focal point of the lens or mirror — the point where parallel rays of light meet, or converge. From the optics the focal length of the mirror can be defined as the radius of the mirror divided between two, or in other words, half the radius of the mirror.

$f = \frac{R}{2}$

$f = \frac{34}{2}$

$f = 17cm$

Therefore the focal length of the mirror is 17cm