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Amplitude = 5 5 4 3 2 1 0 1 2 3 4 5 y = sinx y = 5sinx ? 2 ? 3? 2 2? University of Minnesota Frequency, Wavelength and Period
wavelength is 2?, then there is one wave every 2?, so the frequency is 1 2? In this case, B= 2, so there are two waves every 2?, or one wave every ?, so the frequency is 1 ? Notice that when B= 2, the frequency doubled, and the period is cut in half 8 (a)For y = sin(4x), the wave should be four times as narrow, so that instead of going
7 The wavelength or period is ? 8 The idea of frequency is more intuitive to physicists The frequency of a wave the is number of waves that are completed in one unit of time, or in this case, one unit on the x-axis If the wavelength is 2?, then there is one wave every 2?, so the frequency is 1 2? In this case, B = 2,
The frequency, f, is 1/T, so the equation relating wave speed, frequency, and wavelength is v = f This equation (Equation 21 1), in this form, makes it look like speed is determined by frequency and wavelength, but this is not the case – the speed is determined by the medium A good example is the speed of a wave on a stretched string
So a small instrument creates short-wavelength sounds Similar arguments hold that a large instrument creates long-wavelength sounds The relationship of the speed of sound, its frequency, and wavelength is the same as for all waves: vw = f ; (1) where v w is the speed of sound, f is its frequency, and is its wavelength The wavelength of a sound
frequency, wavelength, and polarization Furthermore, the distribution of these properties in a set of emitted photons carries information We need units for describing the radiation Since all photons travel at the speed of light (3x1010 cm/s), we can write the relationship: ln = c (2 1) where ? is the wavelength, ? is the frequency, and c is