A narrow beam of sound produced by a siren passes from medium A into medium B. The speed of sound in medium A is twice the speed in medium B. The siren continues to operate at a fixed frequency throughout the experiment.
(i) State the physical quantities that define a wave and write the relation that connects them.
(ii) Using the relation stated in (i), explain qualitatively how the wavelength of the sound must adjust as the wave passes from medium A into medium B while the frequency remains unchanged.
(iii) Describe one everyday situation in which this adjustment of wavelength at a boundary is important or observable.