Q1. A ray of light is incident on a plane mirror normal to its surface. The angle of incidence and the angle of reflection are:
A 90°, 90° respectively
B 90°, 0° respectively
C 0°, 90° respectively
D 0°, 0° respectively Correct
Explanation
The angle of incidence is measured between the incident ray and the normal to the reflecting surface. If the ray falls normally on a plane mirror, it travels along the normal itself, so the angle of incidence is 0°. By the law of reflection, the angle of reflection equals the angle of incidence; therefore the reflected ray also makes 0° with the normal and retraces the same path. Choices containing 90° confuse the normal with the mirror surface, so they do not match the definition of the angle.