Physics (AS & A Level) · May / June 2020 · Paper 13 · Question 24

A loudspeaker is set up at the open end of a closed tube containing powder. When the loudspeaker produces sound of frequency 1200 Hz, a stationary wave is produced in the tube. The powder gathers at the nodes of the stationary wave as shown. The speed of sound in the air is 336 m s$^{-1}$. What is the value of distance $x$?

1. A28 cm
2. B42 cm
3. C84 cm
4. D112 cm

As printed in the paper