Question

A spherical mirror and a thin spherical lens have each a focal length of -15 cm. The
mirror and the lens are likely to be
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Answer 1

Answer:

A spherical mirror and a thin spherical lens both have a focal length of -15cm. The mirror and the lens are likely to be- The mirror and the lens are likely to be- concave.

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Answer 2

Both are concave.

Alternative answer that should be given credit:Plano-concave lens