question_answer

A ray of light is incident on a plane mirror at an angle of \[{{60}^{o}}\]. The angle of deviation produced by the mirror is

A)  \[{{120}^{o}}\]                                

B)  \[{{30}^{o}}\]

C)  \[{{60}^{o}}\]                                   

D)  \[{{90}^{o}}\]

Correct Answer: C

Solution :

Here, angle of incidence, \[i={{60}^{o}}\] \[\therefore \] Angle of deviation                 \[\delta ={{180}^{o}}-(i+r)\]                 \[={{180}^{o}}-2i\]                           \[(As\,i=r)\]                 \[={{180}^{o}}-2\times {{60}^{o}}={{60}^{o}}\]