A camera with interchangeable lenses produces an image of a distant 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 size of the image on the film is directly proportional to the focal length of the lens used. The ratio of the focal lengths (135 mm / 50 mm = 2.7) can be used to find the new image width: 3.0 mm * 2.7 = 8.1 mm.

A Camera with Interchangeable Lenses Produces an Image of a Distant