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 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
ANS (a) both concave
