PASCO PS-2006 GLX Power Amplifier - Manual (Page 20)

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P S - 2 0 0 6 G L X P o w e r A m p l i f i e r S a m p l e E x p e r i m e n t s : S t a n d i n g W a v e o n a S t r i n g
18
Standing Wave on a String
In this experiment, the Power Amplifier outputs a variable-frequency
sine wave to drive a vibrating string.
Theory
For any wave with wavelength
λ and frequency f, the speed
V is
(eq. 2)
The speed of the wave is also given by
(eq. 3)
where F is the tension in the string, and
µ is the linear density
(mass/length) of the string.
In this experiment, the string vibrator drives a string. At certain driving
frequencies, a standing wave occurs with an integer number of vibrating
segments. The wavelength is equal to the length of 2 segments. If the
length of the string is L, then
(eq. 4)
Combining equations 2, 3, and 4 yields
(eq. 5)
If F, L and
µ are constant, then the slope of the f versus n graph is equal
to .
Set-up
1. Set up the equipment as illustrated (Figure 13).
2. Use two patch cords to connect the Power Amplifier to the string
vibrator.
3. Configure the Output screen as illustrated (Figure 14).
Figure 13: Equipment Set-up
Mass
~400g
String
1–2 m
String
Vibrator
Additional Equipment Part Number
String Vibrator WA-9857
Patch Cords (2) SE-9750 or SE-9751
Super Pulley ME-9450
String (about 2 m) ME-9876
Hanging Mass (about 400 g)
Rods and clamps (as pictured)
V
λf
=
V
F
µ
--- =
λ
2L
n
------ = n 1 2 3
… , , ,
=
f
n
2L
------ F
µ
--- =
F µ ⁄ 2L ( ) ⁄
Figure 14: Output Setup