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Two plane mirrors A and B are aligned parallel to each other as shown. A light ray is incident at an angle of $30^{\circ}$ at a point just inside one end of A. The plane of incidence coincides with place of figure. The maximum number of time the ray undergoes reflections (including the first one ) before it emerges out is


$(a)\;28 \\ (b)\;30 \\ (c)\;32 \\ (d)\;34 $

1 Answer

We see that each triangle is an equilateral triangle, the side of the triangle is $0.2/ \sqrt {3}$.
Number of reflections $= \large\frac{2 \sqrt 3}{\Large\frac{0.2}{\sqrt 3}}$
$\qquad= 30$
Hence b is the correct answer.
answered Feb 18, 2014 by meena.p
edited Jul 28, 2014 by meena.p
How did you get side of the triangle a 0.2/root 3..? Can please make this question understandable in a easy way. Please reply urgently.

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