(a) Define ultrasonic sound.
(b) An ultrasonic transducer is capable of producing frequencies in the range 1MHz to 15MHz. Explain qualitatively how the wavelength of the sound produced by the transducer depends on (i) the chosen frequency within this range and (ii) the medium through which the sound propagates.
(c) The speed of sound in air at room temperature is about 340ms−1, whereas in soft biological tissue it is approximately 1540ms−1. For the same emitted ultrasonic frequency, which medium will give the shorter wavelength? Justify your answer on the basis of your explanation in part (b).