(a) If the image formed by a mirror for all positions of the object placed in front of it is always diminished, erect and virtural, state the type of the mirror and also draw a ray diagram to justify your answer. Write one use such mirrors are put to and why?
(b) Define the radius of curvature of spherical mirrors. Find the nature and focal length of a spherical mirror, whose radius of curvature is + 24 cm.

Explanation

(a) When the image of object for all positions in front of mirror is diminished, erect and virtual, the mirror must be convex. In Fig. A'B' is virtual, erect and diminished image of object AB held in front of a convex mirror. A convex mirror is used as a rear view mirror by drivers of automobiles.
(b) Radius of curvature of a spherical mirror is the radius of the sphere of which spherical mirror is a part.
When `R = +24 cm`
`f = R//2 = + 24/2 = + 12 cm`
The mirror is convex mirror.