Question

State the direction of incident ray which after reflection from a spherical mirror retraces its path:

• A. Incident ray hits the mirror surface normally at any point
• B. Incident ray hits the mirror parallel to the principal axis
• C. Incident ray hits the mirror surface making an acute angle with respect to the principal axis
• D. None of the above

Answer 1

The correct option is A Incident ray hits the mirror surface normally at any point

If a ray is incident normally on a point on the spherical reflecting surface, the angle of incidence, $i=0$. So, the angle of refraction, $r=0$. Therefore, the ray retraces its own path after reflection. And such a ray travels through the centre of curvature of the mirror.