Physics · Oct / Nov 2017 · Paper 12 · Question 22

A solid plastic cylinder is immersed in a liquid of refractive index 1.4. Light travelling in the plastic cylinder strikes the inside surface at an angle of incidence of 70°. The light undergoes total internal reflection. What are the values of the critical angle in the plastic and the refractive index of the plastic?

1. Agreater than 70°; greater than 1.4
2. Bgreater than 70°; less than 1.4
3. Cless than 70°; greater than 1.4
4. Dless than 70°; less than 1.4

As printed in the paper