Physics (AS & A Level) · Oct / Nov 2024 · Paper 12 · Question 31

A horizontal glass tube, closed at one end, has a layer of dust laid inside it on its lower side. Sound is emitted from a loudspeaker that is placed near the open end of the tube. The frequency of the sound is varied and, at one frequency, a stationary wave is formed inside the tube so that the dust forms small heaps. The distance between four heaps of dust is 30 cm. The speed of sound in the air in the tube is 330 m s⁻¹. What is the frequency of the sound emitted by the loudspeaker?

1. A1650 Hz
2. B2200 Hz
3. C3300 Hz
4. D6600 Hz

As printed in the paper