Question

Both a spherical mirror and a thin spherical lens have a focal length of (-)15

cm. What type of mirror and lens are these?​

Answer 1

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.

Answer 2

Answer:

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