Physics (AS & A Level) · Oct / Nov 2021 · Paper 12 · Question 24

A sound wave from a loudspeaker is reflected back along its original path by a reflector. A microphone is initially at point X where the sound intensity is a minimum, as shown. The microphone is moved towards the reflector and passes through four more intensity minima until reaching a fifth minimum at point Y. The distance XY is 70.0 cm. What is the wavelength of the sound?

1. A11.7 cm
2. B14.0 cm
3. C23.3 cm
4. D28.0 cm

As printed in the paper