Spherical mirrors: An object is 12 cm in front of a concave spherical mirror, and the image is 3.0 cm in front of the mirror. What is the focal length of the mirror?

Question

Quizplus · Accepted Answer

The image is virtual and upright, so the mirror is concave. The object distance is 12 cm and the image distance is 3.0 cm. Using the thin lens equation, 1/f = 1/do + 1/di, we get 1/f = 1/12 cm + 1/3.0 cm = 1/4.0 cm. Therefore, the focal length of the mirror is 4.0 cm.

Spherical Mirrors: an Object Is 12 Cm in Front of a Concave