The three angles of a glass prism are 45°, 45° and 90° as shown in Fig. 4.1. [Figure 4.1] At point Y, a ray of light of a single frequency travels in air and strikes the side of the prism at 90°. The ray passes into the glass prism.

1. (a)(i)Light travels more slowly in glass than in air. State what happens to the wavelength of the light in the ray as it enters the glass.[1]
2. (a)(ii)State what happens to the frequency of the light in the ray as it enters the glass.[1]
3. (b)(i)The refractive index of glass is 1.6. Calculate the critical angle for light in glass.[2]
4. (b)(ii)On Fig. 4.1, sketch the path of the light after it strikes the side of the prism at Z and after it returns to the air.[2]

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