During an ocean-mapping survey, a research vessel emits a continuous underwater acoustic signal at a frequency of 12.0 kHz. At the survey location, sound travels through seawater at a speed of 1.50×103m s−1. The signal also propagates into the air directly above the ship, where the speed of sound is 340m s−1.
(1) Calculate the wavelength of the acoustic signal while it travels through seawater. Give your answer in metres and include appropriate significant figures.
(2) Assuming the frequency of the sound does not change when the wave crosses the water–air boundary, determine the wavelength of the same sound in air. Provide your answer in metres and briefly comment on what this comparison illustrates about a property of waves at an interface.