Physics (AS & A Level) · Feb / March 2019 · Paper 12 · Question 24

A straight tube is closed at one end and has a loudspeaker positioned at the open end. The frequency of the loudspeaker is initially very low and is increased slowly. A series of loudness maxima are heard. The stationary wave which gives the first maximum has a node at the closed end and an antinode at the open end. The frequency of the loudspeaker is f1 when the first maximum is heard. What is the frequency of the loudspeaker when the fourth maximum is heard?

1. A\frac{7f_1}{4}
2. B2f_1
3. C4f_1
4. D7f_1

As printed in the paper