A submarine operating in seawater at a temperature of 20∘C emits a sonar pulse of frequency 10kHz. In this region of the ocean the speed of sound is 1482ms−1. The pulse subsequently enters a colder layer of water at 5∘C where the speed of sound is 1440ms−1.
(i) Calculate the wavelength of the sonar pulse in the 20∘C layer.
(ii) Calculate the wavelength of the same pulse in the 5∘C layer.
(iii) Determine the percentage change in wavelength as the pulse crosses from the warm layer to the cold layer.
(iv) State, with reason, whether the frequency of the sonar pulse changes on moving from one layer to the other.