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24.2 Standing Waves
24.2
A wave that is confined in a space is called a standing wave.
Standing waves on the vibrating strings of a guitar produce the
sounds you hear. Standing waves are also present inside the chamber
of a wind instrument.
A string that contains a standing wave is an oscillator. Like any
oscillator, it has natural frequencies. The lowest natural frequency is
called the fundamental. Other natural frequencies are called
harmonics. The first five harmonics of a standing wave on a string
are shown to the right.
There are two main parts of a standing wave. The nodes are the
points where the string does not move at all. The antinodes are the
places where the string moves with the greatest amplitude.
The wavelength of a standing wave can be found by measuring the length of two of the bumps on the string.
The first harmonic only contains one bump, so the wavelength is twice the length of the individual bump.
1.
Use the graphic below to answer these questions.
a.
Which harmonic is shown in each of the strings below?
b.
Label the nodes and antinodes on each of the standing waves shown below.
c.
How many wavelengths does each standing wave contain?
d.
Determine the wavelength of each standing wave.