Question

A light ray, travelling in glass medium, is incident on the glass–air interface at an angle θ . The reflected (R) and the transmitted (T) intensities, are both plotted, as functions of θ . The correct graph is the graph labelled as

Answer 1

Correct answer is (3)

At θ = 0° ; R + T = 1. However, R is not zero and T is not 1. As θ increases, from 0° to the critical angle θ_C ; T decreases and R increases. For θ > θ_C , upto 90° ; there is no transmitted beam; therefore, T = 0. Over this range, due to T.I.R, 100% of incident light is reflected back, i.e., R = 1. 

These variation are correctly shown only in graph (3).