Physics (AS & A Level) · Feb / March 2019 · Paper 12 · Question 28

Two identical loudspeakers are connected in series to an a.c. supply, as shown. [diagram: a.c. supply connected to two speakers in series; line PQ to the right] A microphone is moved along the line PQ. Which graph best shows the variation with distance from P of the intensity of the sound detected by the microphone?

1. AGraph A: intensity against distance from P to Q, showing a varying amplitude with a minimum (zero) at P and increasing amplitude towards Q
2. BGraph B: intensity against distance from P to Q, showing a minimum (zero) at P and roughly constant amplitude oscillations
3. CGraph C: intensity against distance from P to Q, showing a maximum at P and roughly constant amplitude oscillations
4. DGraph D: intensity against distance from P to Q, showing a maximum at P and roughly constant amplitude oscillations

As printed in the paper