A ray of light is incident at an angle of 30°
between two parallel mirrors as shown in the fig, at a
point just inside one end of A.The plane of incidence coincides with the plane of the fig. The
maximum number of times, the ray undergoes reflection (including first one) before emerging out
between two parallel mirrors as shown in the fig, at a
point just inside one end of A.The plane of incidence coincides with the plane of the fig. The
maximum number of times, the ray undergoes reflection (including first one) before emerging out
Answers & Comments
Answer:
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
0
.
From the figure,
tan30
∘
=
0.2
d
=
3
1
or, d=
10
3
2
m
The ray will not undergo reflection after it emerges out of the arrangement, i.e., after the ray covers 2
3
m
Therefore the maximum number of reflections that occur =
10
3
2
2
3
=30