Question

Diagram alongside shows the path of ray AB through an isosceles prism ‘PQR’. What is the magnitude of

1. angle of incidence on face PR?
2. angle of incidence on face PQ?
3. angle of emergence on face QR?

Answer 1

The ray strikes face PR normally, so its angle of incidence is 0°. Inside the prism, it strikes face PQ at 45° to the normal. After reflection at PQ, it reaches face QR normally and emerges without deviation.

1. Angle of incidence on PR = 0°
2. Angle of incidence on PQ = 45°
3. Angle of emergence from QR = 0°