(b) A transmitter produces microwaves that travel in air towards a metal plate, as shown in Fig. 4.1. [Figure 4.1] The microwaves have a wavelength of 0.040m. A stationary wave is formed between the transmitter and the plate.

1. (a)State the principle of superposition.[2]
2. (b)(i)Explain the function of the metal plate.[1]
3. (b)(ii)Calculate the frequency, in GHz, of the microwaves. frequency = ..................................................... GHz[3]
4. (b)(iii)1.A microwave receiver is initially placed at position X where it detects an intensity minimum. The receiver is then slowly moved away from X directly towards the plate. 1. Determine the shortest distance from X of the receiver when it detects another intensity minimum. distance = ..................................................... m[1]
5. (b)(iii)2.2. Determine the number of intensity maxima that are detected by the receiver as it moves from X to a position that is 9.1 cm away from X. number = .....................................................[2]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.