Two plane mirrors are inclined at angle ‘θ’ as shown in figure. If a ray parallel to OB strikes the other mirror…..

Q.Two plane mirrors are inclined at angle ‘θ’ as shown in figure. If a ray parallel to OB strikes the other mirror at P and finally emerges parallel to OA after two reflections then θ is equal to
Ray Optics
(a) 90°
(b) 60°
(c) 45°
(d) 30°
Ans: B

Sol: Let i is the angle of incidence at mirror OB (draw the figure by applying Law of Refraction )

2θ+90 -i = 180 and 90-i = θ

2θ+ θ = 180

θ=60

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