A coin is 12 cm in front of a converging lens with focal length of magnitude 4.0 cm. Where is the image?
A) 6.0 cm behind the lens
B) 6.0 cm in front of the lens
C) 4.0 cm in front of the lens
D) 8.0 cm behind the lens

Question

Quizplus · Accepted Answer

The lens equation is 1/f = 1/v + 1/u, where f is the focal length, v is the image distance, and u is the object distance. Substituting f = 4.0 cm and u = 12 cm (positive because the object is in front of the lens), we solve for v to find the image distance. Rearranging the lens equation gives 1/v = 1/f - 1/u = 1/4 - 1/12 = 3/12 - 1/12 = 2/12 = 1/6. Therefore, v = 6 cm, and since v is positive, the image is behind the lens.

A Coin Is 12 Cm in Front of a Converging