A concave mirror has a radius of curvature of 60.0 cm.How close to the mirror should an object be placed so that the rays travel parallel to each other after reflection?
A)10.0 cm
B)15.0 cm
C)30.0 cm
D)45.0 cm
E)60.0 cm

Question

Quizplus · Accepted Answer

For a concave mirror, when an object is placed on the focal point, rays parallel to each other will be reflected back parallel to each other. The focal length of the mirror is half the radius of curvature, which gives us a focal length of 30.0 cm. Using the mirror formula, 1/f = 1/do + 1/di, where f is focal length, do is object distance, and di is image distance, we can solve for do:
1/30.0 = 1/do + 1/60.0
Solving for do, we get do = 30.0 cm. Therefore, the object should be placed 30.0 cm away from the mirror, which is given by choice C.

A Concave Mirror Has a Radius of Curvature of 60