Question

A spherical mirror and a thin spherical lens each have a focal length of -15 cm.The mirror and lens are likely to be-
1 point
Both concave
Both convex
Mirror is concave, lens convex
Mirror is convex, lens concave​

Answer 1

Hey there!

Amongst convex and concave mirrors according to sign convention we can say that a concave mirror has a negative focal length

similarly if check the sign convention for a concave lens the focal length of a concave lens is also negative

so your answer is both concave

Hope it helps!