# A spherical mirror and a thin spherical lens

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

(a) Both concave

(b) Both convex

(c) The mirror is concave and the lens is convex

(d) The mirror is convex, but the lens is concave

solution:
Option (a) is correct i.e., a concave mirror as well as concave lens both have negative focal length