The focal length of a concave mirror has a magnitude of 20 cm.What is its radius of curvature?
A)10 cm
B)40 cm
C)-40 cm
D)20 cm
E)-20 cm

Name: The focal length of a concave mirror has a magnitude of 20 cm.What is its radius of curvature? A)10 cm B)40 cm C)-40 cm D)20 cm E)-20 cm
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Question

Quizplus · Accepted Answer

The radius of curvature is twice the focal length for a concave mirror.
So, r = 2f = 2 x 20 cm = 40 cm. 
Therefore, the correct answer is option B.

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