## Physics: Principles with Applications (7th Edition)

The waves have the same speed v. The wave speed is related to the frequency and wavelength by $v=f \lambda$ so the wave with half the wavelength as the other has twice the frequency. From equation 11–18 we see wave intensity is proportional to the square of the frequency f. The wave with the shorter wavelength has 4 times the intensity as the other wave, i.e., transmits four times the energy in the same time interval.