Physics - Representing sound waves with displacement graphs
Representing sound waves with displacement graphs
Alternatively, a sound wave may be represented by a graph of displacement
or position against time. In this case the frequency and period of the wave
are unchanged in their definitions but it is easier to see what the term
wavelength means. The wavelength  of a sound wave is the minimum
distance that the wave travels during the time of one complete cycle. It
can also be defined as the distance between successive points in a wave
which are in phase, i.e. particles in the wave that are experiencing
identical behaviour. By definition, these particles would be separated by
one full period.
The amplitude  of a sound wave is defined as the maximum displacement
of a particle from its undisturbed or mean position. The amplitude of a
sound wave determines its loudness. However, the relationship between
amplitude and loudness is complex (discussed in section). Sounds of larger
amplitude can only be created when the vibrating source physically covers a
larger distance, forcing the particles of the medium to move further from
their undisturbed or mean positions. That is, more energy is put into the
vibrating source and a louder sound results.
The diagram allows you to use the slides indicated to alter the values of
frequency, period, wavelength and amplitude of the presented soundwave.
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