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Re: Standing waves.

First guess is so that the length of the string
at maximum amplitude is ( nearly) constant.
Probably lots of complex stuff as well.

Roger Haar

Ludwik Kowalski wrote:

How to explain this in an introductory physics course?

Standing waves apparatus from Pasco is
used to observe loops established on a
string at frequencies corresponding to the
known L, tension, and mu. In preparing for
tomorrow's lab I saw that the amplitudes of
loops decrease monotonically (from about
4 cm when the lambda is 2*L to about 0.2
cm when lambda is 9 times shorter.)
Why is it so?

My setup: Pasco vibrator SF-9324
Soft threaded string mu=0.00160 kg/m and
L=126.5 cm,
Pasco generator (amplitude was constant (in
the middle of the range) only frequencies were
changed from about 14 Hz to 128 to observe
1, 2, 3, 4, ...9 loops.

Why do the amplitudes of standing waves
decrease while the signal amplitude of the
source remains the same?
Ludwik Kowalski