A monochromatic beam of light enters a square enclosure with mirrored interior surfaces at an angle of incidence θ_i (≠0) (see the figure below). For some value(s) of θ_i , the beam is reflected by every mirrored wall (other than the one with the opening) exactly once and exits the enclosure through the same hole. Which of the following statements about this beam is correct?

Question

A monochromatic beam of light enters a square enclosure with mirrored interior surfaces at an angle of incidence θ_i (≠0) (see the figure below). For some value(s) of θ_i , the  beam is reflected by every mirrored wall (other than the one with the opening) exactly once and exits the  enclosure through the same hole. Which of the following statements about this beam is correct?

Examsnet · Accepted Answer

Correct Answer is :  The beam will come out only at  θi=45°

KVPY 2020-21 SA Exam Previous Papers