Question

A light ray incident normally on a plane mirror suffers a deviation of

• A. 0°
• B. 90°
• C. 180°
• D. 360°

Answer 1

The correct option is C

180°

1. Law of reflection of light states that,
   1. Angle of incidence = Angle of reflection
   2. $\Rightarrow \angle \mathrm{i}=\angle \mathrm{r}$
2. In case of normal incidence,
3. $\angle \mathrm{i}=\angle \mathrm{r}=0°$
4. The ray of light retraces its path when the incident is normal.
5. Thus, it gets deviated by an angle of $180°$.

Hence, the correct option is (C).