The bellows of an adjustable camera can be extended so that the largest film to lens distance is one and one-half times the focal length.If the focal length is 12 cm, the nearest object which can be sharply focused on the film must be what distance from the lens?
A)12 cm
B)24 cm
C)36 cm
D)48 cm
E)72 cm

Question

Quizplus · Accepted Answer

Using the lens formula 1/f = 1/v + 1/u, where f is the focal length, v is the image distance (film to lens distance), and u is the object distance. Given f = 12 cm and the largest film to lens distance (v) is 1.5 times the focal length, v = 18 cm. Substituting these values into the lens formula and solving for u gives the nearest object distance as 36 cm.

The Bellows of an Adjustable Camera Can Be Extended So