An ultrasonic transmitter emits a continuous wave of frequency 40kHz in air, where the speed of sound is 340ms−1. The wave then enters pure water in which the speed of sound is 1480ms−1. Neglect any energy losses at the boundary.
(i) Calculate the wavelength of the ultrasonic wave in air.
(ii) Determine its wavelength in water.
(iii) Find the ratio of the two wavelengths and interpret the result physically.
(iv) Would the time period of the wave change after it enters water? Give a reason for your answer.