O-LevelPhysicsLight5054/22 · May/June 2022 · Q47 Marks

Fig. 4.1 shows a ray of white light incident on a glass prism. [Figure 4.1] Refraction causes the white light to separate into different colours.

(a)Define the term 'angle of refraction'.[2]
(b)The angle of incidence of the white light as it enters the prism is 40° and the angle of refraction for the red light is 25°. Calculate the refractive index of the glass for red light. Show your working.[2]
(c)Using Fig. 4.1, state and explain how the refractive index for red light differs from the refractive index for violet light.[2]
(d)The source of white light used in Fig. 4.1 produces other types of electromagnetic radiation as well as visible light. State the name of the invisible radiation found at P and the invisible radiation found at Q.[1]

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Mark scheme

Marking points from the official mark scheme (May/June 2022). The mark or mark type is shown in brackets.

[1] clear angle is to / from the normal
[1] angle between/with the refracted ray / beam and the normal or vv OR angle from the normal to the refracted ray / beam or vv
[1] (refractive index = ) sini/sinr algebraic or numerical in any form
[1] 1.5
[1] refractive index smaller (for red)
[1] larger angle of refraction (for red) OR (red) bends / refracts less (towards normal)
[1] P infrared and Q ultraviolet

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