Question

infinite images are seen when 2 plane mirrors are kept parallel to each other.Why?

Why do these images get fainter as their distance from mirror increases ?

Answer 1

The number of images formed (n) depends upon the angles between them (θ) as

n = (360^o/θ) -1

now, in this case as the mirrors are placed parallel to each other, θ = 0^o

so,

n = (360/0) - 1 = infinity

thus, number of images will be infinite.

As the object is kept between the two mirrors, it undergoes multiple reflection to produce the distant object. At each reflection, the intensity of the incident light gets lost due to the absorption phenomena. Each reflected beam has lesser energy than the incident. Hence, the distant images get fainter and fainter.