A ship’s foghorn emits a steady note of frequency 400Hz. A sensor placed 250m below the sea surface detects this sound after it has travelled through air and then sea water.
(a) Calculate the wavelength of the sound in air, taking the speed of sound in air as 340m/s.
(b) Calculate the wavelength of the same sound in sea water where its speed is 1500m/s.
(c) How many complete wavelengths fit in the vertical distance between the ship’s horn and the sensor under water?
(d) Comment on what happens to the frequency and wavelength of the sound as it passes from air to water.