Question

A candle is sitting in front of a concave mirror at a distance of 12.2 cm. It is found that an image of the candle appears at 25.0 cm. What is the focal length of the mirror?

Answer 1

Focal length (f) = 1/2 (Object distance + Image distance)

f = 1/2 (12.2 cm + 25.0 cm)

f = 18.6 cm