A mirror with a focal length -25 cm has a 4.0 cm tall object placed 100 cm in front of it. What is the position of the image?
A)20 cm behind the mirror
B)25 cm behind the mirror
C)100 cm in front of the mirror
D)25 cm in front of the mirror
E)20 cm in front of the mirror

Question

Quizplus · Accepted Answer

The image is formed 20 cm behind the mirror. This can be determined using the thin lens equation: 1/f = 1/do + 1/di, where f is the focal length, do is the object distance, and di is the image distance. Plugging in the given values, we get: 1/-25 cm = 1/100 cm + 1/di. Solving for di, we get: di = -20 cm.

A Mirror with a Focal Length -25 Cm Has a 4.0