Question

both a spherical mirror and a thin spherical lens have a focal length of (-) 15cm what type of mirror and lens are these​

Answer 1

Explanation:

ANSWER

By convention, the focal length of a concave mirror and a concave lens are taken as negative. Hence, both the spherical mirror and the thin spherical lens are concave in nature.

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Answer 2

Explanation:

since the focal length is negative i.e. f=-15 cm ,the spherical lens is concave lens as the focal length is negative for diverging lens and in case of mirrors, it is convex mirror where the focal length is negative.