A wave travels from medium 1 into medium 2.
(i) Show that the frequency of the wave remains the same when it crosses the boundary between the two media.
(ii) Using the result of part (i), derive an expression for the ratio λ1λ2 in terms of the speeds v2 and v1 of the wave in the two media.
(iii) Water waves move from a deep region where their speed is 1.5m/s to a shallow region where their speed is 1.0m/s. If the wavelength in deep water is 3.0cm, calculate the wavelength in shallow water.