A camera with changeable lenses produces an image of an object that is 3.0 mm wide on the film when the 50.0 mm lens is used.When the 135 mm lens is used,how wide is the image of the object on the film?
A) 3.0 mm
B) 85 mm
C) 4.5 mm
D) 0.37 mm
E) 8.1 mm

Question

Quizplus · Accepted Answer

The image size is proportional to the focal length of the lens. The ratio of the focal lengths is 135/50 = 2.7. Therefore, the image size with the 135 mm lens is 3.0 mm * 2.7 = 8.1 mm.

A Camera with Changeable Lenses Produces an Image of an Object