(a)[2]
Define what is meant by the term ‘angle of refraction’.
(b)[2]
As the white light enters the prism, its angle of incidence is $40^\circ$ and the angle of refraction for the red light is $25^\circ$. Calculate the refractive index of the glass for red light. Show your working.
(c)[2]
Using Fig. 4.1, state and explain in what way the refractive index for red light is different from that for violet light.
(d)[1]
The white-light source in Fig. 4.1 emits other forms of electromagnetic radiation in addition to visible light. State the name of the invisible radiation at P and the invisible radiation at Q.