Question

Match the incident rays with the reflected rays after they reflect off a spherical mirror.

• A. At focus
• B. Rays retrace
• C. To infinity

Answer 1

Any incident ray travelling parallel to the principal axis (from infinity) of a spherical mirror will pass through (in case of a concave mirror) or appear to pass through (in case of a convex mirror) the principal focus. Conversely, the light rays imagined to start from the principal focus would travel parallel to the principal axis towards the infinity, after they have hit the mirror. If a light ray is emitted from the centre of curvature towards the mirror in any angle to the principal axis, it always retraces the path because any line from the centre of curvature to the mirror is considered as a normal.