question_answer

Two plane mirrors are inclined to each other at some angle. A ray of light incident at \[30{}^\circ \] on one, after reflection from the other retraces its path. The angle between the, mirrors is

A) \[30{}^\circ \]

B) \[45{}^\circ \]

C) \[60{}^\circ \]  

D) \[90{}^\circ \]

Correct Answer: A

Solution :

[a] 

\[\angle i=\angle r={{30}^{o}}\]

\[\therefore \]      \[\angle OIQ={{60}^{o}}\]

\[\therefore \]      \[IOQ={{90}^{o}}-{{60}^{o}}={{30}^{o}}\]