Sound waves, like waves on a string, can produce stationary waves inside air columns.
A physics technician demonstrates how sound can set up stationary waves using a tall tube of cross-sectional area 4.0 × 10–3 m2 and a loudspeaker connected to a signal generator, as shown in Fig. 1.1.
Fig. 1.1
The signal generator is switched on so that sound waves enter the tube. He slowly pours water into the tube and the sound gradually increases in volume, reaching a first maximum at a particular instant. Immediately after the volume begins to decrease.
Water continues to be added until the volume rises again, reaching a second and final maximum after a further 3.2 × 10–3 m3 of water is poured in.
Determine the wavelength of the sound waves.