# © Oxford University Press 2011 IP1.24.5 The wave equation The wave equation.

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© Oxford University Press 2011 IP1.24.5 The wave equation The wave equation

© Oxford University Press 2011 IP1.24.5 The wave equation The wave equation The speed of a wave depends on its frequency and its wavelength. They are related. If the wave speed is called v, the frequency f and the wavelength, then: Wave speed metres/second (m/s) = = frequency hertz (Hz)   wavelength metres (m) v = f

© Oxford University Press 2011 IP1.24.5 The wave equation Dylan is standing on the end of a pier. He measures the water waves going past him. The wavelength of each wave is 1.3 m. He counts 2 waves every second. Find the wave speed. Wave speed = frequency  wavelength v = 2 Hz  1.3 m v = 2  1.3 m/s v = 2.6 m/s

© Oxford University Press 2011 IP1.24.5 The wave equation Find the speed of a wave whose wavelength is 40 m and frequency is 100 Hz. Wave speed = frequency  wavelength v = 100 Hz  40 m v = 100  40 m/s v = 4000 m/s

© Oxford University Press 2011 IP1.24.5 The wave equation A flute produces a note with a wavelength of 75 cm. The speed of sound is 330 m/s. Find the frequency of the note. frequency = frequency = 440 Hz wave speed wavelength 330 m/s 0.75 m

© Oxford University Press 2011 IP1.24.5 The wave equation What is the frequency when the wave speed is 450 m/s and the wavelength is 4.6 m? frequency = frequency = 97.8 Hz wave speed wavelength 450 m/s 4.6 m

© Oxford University Press 2011 IP1.24.5 The wave equation A radio station transmits waves with a frequency of 120 MHz. The radio waves travel at 3  10 8 m/s. Find the wavelength of the radio waves. wavelength = wavelength = 2.5 m wave speed frequency 3  10 8 m/s 1.2  10 8 Hz

© Oxford University Press 2011 IP1.24.5 The wave equation A speaker produces sound at a frequency of 6.6 kHz. The speed of sound is 330 m/s. Calculate the wavelength. wavelength = = = 0.05 m = 5 cm wave speed frequency 330 m/s 6600 Hz