Question

Two plane mirrors A and B
are aligned parallel to each
other, as shown in the
figure. A light ray is incident
at an angle 30' at a point
just inside at one end of A.
The plane of incidence
coincides with the plane of
the figure. The number of
times the ray undergoes
reflection (including the
first one) before it emerges
out is​

Answer 1

Answer:

Answer is 30

Let the distance covered by the ray after reflection from a surface be 'd'.

From the first law of reflection and alternate angle property, all the angles shown in the figure are equal to 30 degrees.

From the figure,

30°=d/0.2m = 1/√3

d = 2/√3m

It won't go reflection after it emerges out of the arrangement that is after the ray covers 2√3m

Therefore the maximum number of reflections that occur are

2√3/2/10√3 = 30