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Sensing and Datalogging for Science Education |
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Sciencescope |
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Last updated 31st July 2008 Sensors Logbooks PriceLists Investigations 2008 Catalogue |
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Frequency of a waveThe most important characteristics of a wave are its wavelength, frequency, and amplitude. A picture of a wave is shown below with the wavelength and amplitude marked:
This
picture represents amplitude against LENGTH. The
wavelength (λ) of a wave is the distance between two successive
peaks of the wave. The
frequency (f) of a wave is the number of cycles that pass the
observer in a given time. Hertz is the unit of frequency, and just means how many cycles per second. It
is related to the wavelength by the simple relationship: f = v/λ where v is
the velocity of the wave. For light waves, the velocity is equal to the speed of
light, c, (2.998*108 m/s) so for light waves this relationship is f =
c/λ. The
amplitude of a wave is the distance between the peak of a wave and the
midpoint of the wave. Neither the wavelength nor frequency of a wave depends on
the amplitude.
You can also measure the amplitude of a wave against TIME:
Since
frequency and
period are exact inverses of each other, there is a very basic formula you can
use to calculate one from the other: f
= 1 / T
or
T = 1 / f You
are going to record a sound wave and obtain its graph of amplitude against TIME.
View and/or download the worksheet View and/or download the Datadisc file examples of this investigation. (you must have Datadisc installed to view the file, downloadable from Download Centre) |
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