A uniform train of sound waves produced by a siren travels from still air into a region filled with carbon dioxide at the same temperature. Assume there is no reflection at the interface.
(i) Explain, with reference to fundamental definitions of wave speed and frequency, why the frequency of the waves does not change as they cross from air into carbon dioxide.
(ii) Using the same reasoning, describe qualitatively how the wavelength is affected by the change of medium.
(iii) State two possible factors, other than the change in wavelength, that could alter the amplitude of the sound on passing into carbon dioxide, and briefly justify each.
(iv) Summarise your arguments to show that the relation v=λν remains valid in both media without modification.