2024 · M/J · 9702/21 | Q5

0/25parts marked · 0 of 51 marks

Question (5 of 7)8 marks · Practise this topic →

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Available practice: 51 of 60 marks. Parts 1(a), 3(a), 6(d)(i), 6(d)(ii) await marking support. Scores cover available parts only.

A stretched string PQ has length 1.2 m. One end of the string is attached to a vibration generator and the other end is attached to a wall, as shown in Fig. 5.1. The vibration generator is switched on and a stationary wave is formed on the string. The string is shown at one instant of time in Fig. 5.2.

(a)Explain how a stationary wave is formed between the vibration generator and the wall.

Fig. 5.1 — see the question text for what it shows

Fig. 5.2 — see the question text for what it shows

Answer guidance

Explain Give reasons, not just what happens. Each distinct reason is usually worth a mark.

[2 marks]

A stretched string PQ has length 1.2 m, attached at P to a vibration generator and at Q to a wall. A stationary wave is formed on the string, shown at one instant in Fig. 5.2.

(b)Calculate the wavelength of the stationary wave shown in Fig. 5.2.

Answer guidance

Calculate Show your working. The method can earn marks even when the final value is wrong, and a bare answer often cannot.

[1 mark]

A stationary wave is formed on a stretched string PQ of length 1.2 m. Fig. 5.3 shows the stationary wave at time t = 0 when all points on the wave are at their maximum displacements.

The period of the wave is 0.16 s.

(c)On Fig. 5.3, sketch the shape of the stationary wave at time t = 0.24 s.

Fig. 5.3 — see the question text for what it shows

[2 marks]

A stationary wave is formed on a stretched string. Points R and T on the string are a horizontal distance of 0.30 m apart and in the positions shown in Fig. 5.4.

(d)State the phase difference between the oscillations of points R and T.

Fig. 5.4 — see the question text for what it shows

Answer guidance

State A short answer. No explanation is needed, and adding one cannot earn extra marks.

[1 mark]

A stationary wave is formed on a stretched string PQ of length 1.2 m with three loops between P and Q (wavelength found in (b)). The period of the wave is 0.16 s.

(e)Calculate the speed of the progressive waves on the stretched string.

Answer guidance

Calculate Show your working. The method can earn marks even when the final value is wrong, and a bare answer often cannot.

[2 marks]

9702/21/M/J/24Cambridge International AS & A Level Physics 9702 · May/June 2024 · Paper 2 variant 1 · Question 5