Question

Find the angle of deviation for the incident ray.

• A. ${120}^{\circ }$
• B. ${60}^{\circ }$
• C. ${90}^{\circ }$
• D. ${135}^{\circ }$

Answer 1

The correct option is C ${90}^{\circ }$


Here $\angle i=({90}^{\circ }-{45}^{\circ })={45}^{\circ }$
i.e., $\angle r=\angle i={45}^{\circ }$
$\Rightarrow \angle i+\angle r={90}^{\circ }$
Hence, the ray will go horizontally after reflection.
Deviation $\left(\delta \right)={180}^{\circ }-2\angle i={90}^{\circ }$
Hence, option $\left(c\right)$ is the correct answer.