PASCO TD-8565, Instruction Manual And Experiment Manual

Page: 62 / 75

9
012-03489E Sonometer
If the analogy with Newton’s Law is accepted, and it is
assumed that the wave velocity depends only on tension
and linear density, dimensional analysis shows that the
form of the equation must be as it is. There is no other
way to combine tension (with units of MLT
-2
) with linear
density (ML
-1
) to get velocity (LT
-1
).
Of course, the equation must be verified experimentally.
This is done in Experiment 2, in which the linear density
of the string is varied by using different strings. The ten-
sion is varied using hanging weights on a lever arm. The
wavelength is then measured by adjusting the frequency
until a resonance pattern develops. The velocity can then
be calculated using the relationship
V =
λν
, and the effects of tension and linear density on
velocity can be determined.
Experiments
The two experiments are:
• Resonance Modes of a Stretched String
• Velocity of Wave Propagation
Both can be done with a function generator and dual-trace
oscilloscope OR with a computer interface (such as the
CI-6550) and power amplifier.