Question

Fig. shows a right-angled with a ray of light incident on the side AB. (The critical angle for glass is 42°)

1. Copy the diagram and complete the path of the ray of light in and out of the glass prism.
2. What is the value of the angle of deviation shown by the ray?

Answer 1

(a) The ray enters face AB normally, so it passes into the prism without deviation. It then strikes face AC at an angle of incidence \(45^\circ\).

Since

45° > 42°

the ray undergoes total internal reflection at AC. It then travels vertically downward to face BC and emerges normally without deviation.

(b) Angle of deviation:

90°