For a step-index optical fibre with and

PHYSICS · Single correct · A Level · Physics · Waves · Waves

Problem

For a step-index optical fibre with

n_{\text{core}} = 1.50

and

n_{\text{clad}} = 1.48

, the largest possible angle that a light ray in air may make with the fibre axis at entry so that it is guided through the fibre is about (a)

8^{\circ}

(b)

30^{\circ}

(c)

14^{\circ}

(d)

24^{\circ}