PASCO WA-9612 RESONANCE TUBE - Manual (Page 26)

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Resonance Tube 012-03541E
Experiment 4: The Speed of Sound in a Tube
Procedure
➀ We recommend that you use external triggering on
the oscilloscope. You will also have to adjust the
triggering level and holdoff in order to get a clean,
steady trace on the screen.
➁➄ Our measurements gave values of 335-347 m/s,
with the variation mostly due to difficulties in mea-
suring the distance between echoes. The trace is not
always steady and easy to read.
Analysis
➀ v 340 m/s. For better precision, use the method
described in the teacher’s guide to experiment 3.
➁ We were able to measure this by building a corner-
cube reflector out of some scrap lexan sheets and
tape. The signal was very weak, though, and practi-
cally useless beyond 1m.
➂ The reflected sound pulse will be inverted when the
end of the tube is open; and non-inverted when
closed. This indicates—among other things—that
the speed of sound inside the tube is faster than out-
side the tube. (We have not been able to experimen-
tally demonstrate this velocity difference with this
apparatus.)