A spherical mirror and a thin spherical lens each have a focal length of +25 cm. The mirror and the lens are likely to be
A
Both concave
B
Both convex
C
Mirror is concave and lens is convex
D
Mirror is convex and lens is concave
Correct Option:
B
Explanation
Under the Cartesian sign convention, a spherical mirror with positive focal length is a convex mirror, because its focus lies behind the mirror. A thin lens with positive focal length is a convex or converging lens. Therefore both optical devices are convex.
