Red light of frequency 4.7 × 10¹⁴ Hz travels in air at a speed of 3.0 × 10⁸ m/s.

1. (a)Calculate the wavelength in air of this red light. wavelength = ........................................................................ m[3]
2. (b)(i)State what happens to the speed, to the frequency and to the wavelength of the light as it enters the block. speed .......................................................................................................................... frequency ...................................................................................................................... wavelength ....................................................................................................................[2]
3. (b)(ii)Using the angles shown on Fig. 4.1, calculate the refractive index of the glass. refractive index = ........................................................................[3]
4. (b)(iii)The light continues along the path shown in Fig. 4.1 until it strikes the bottom surface of the block. Light then emerges into the air. Draw on Fig. 4.1 to show the path taken by the light until it strikes the bottom surface and the path of the light that emerges into the air.[2]

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