question_answer

Two plane mirrors are inclined to each other ray of light incident on one face at \[30{}^\circ \] after reflection from the second retraces the path. What is the angle between the mirrors?

A)  \[40{}^\circ \]                  

B)         \[60{}^\circ \]                  

C)  \[20{}^\circ \]                  

D)         \[30{}^\circ \]

Correct Answer: D

Solution :

We see from the figure the ray incident on the second mirror\[{{M}_{2}}\]retraces its path (way). This would result the incident ray becomes normally on the second mirrors. Hence the angle between mirros \[{{M}_{1}}\] and \[{{M}_{2}}\]is \[\angle {{M}_{1}}A{{M}_{2}}=30{}^\circ .\]