2017 · Q13
A ray of light is incident on a plane mirror at an angle of 40° with respect to surface normal. When it gets reflected from the mirror, it undergoes a deviation of
General KnowledgePhysics
- A40°
- B100°
- C90°
- D80°
Explanation
The angle of incidence is 40° to the normal, so by the law of reflection the angle of reflection is also 40°. Deviation δ is defined as the angle between the incident ray's original path and the reflected ray: δ = 180° − (i + r) = 180° − 80° = 100°. The 80° figure is only the total angle between the incident and reflected rays, not the deviation from the original path. The ray therefore undergoes a deviation of 100°.