The image formed by the mirror will be in the shape of a :

Question

A concave mirror of radius of curvature 20 cm is shown in the figure. A circular disc of diameter 1 cm is placed on the principle axis of mirror with its plane perpendicular to the principal axis at a distance 15 cm from the pole of the mirror. The radius of disc starts increasing according to the law r = (0.5 + 0.1 t) cm/sec where t is time is second.

The image formed by the mirror will be in the shape of a :

(A) circular disc 

(B) elliptical disc with major axis horizontal 

(C) elliptical disc with major axis vertical 

(D) distorted disc

Answer 1

Correct option: (A) circular disc

Explanation:

All dimensions of the disc are perpendicular to the principal axis. Hence all dimensions are equally magnified, resulting in an image in the shape of a circular disc.