A bat in flight emits an ultrasonic pulse of frequency 40 kHz in air, where the speed of sound is 340 m/s. The same pulse enters water, in which the speed of sound is 1500 m/s, without any change in frequency.
(i) Calculate the time period of the ultrasonic wave.
(ii) Find the wavelength of the wave in air.
(iii) Compute the wavelength of the wave in water.
(iv) Comment on how your answers illustrate the dependence of speed and wavelength on the medium while frequency remains unchanged.