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Periodic Phenomena
Kundt's tube with analog outputs
Ref : 22204
We observe from the recording that the experimental points are quite scattered at the
closed end (between the abscissa 0 and 1.5 cm): The cause could be the nature of the
material which covers the inside of the cover (adhesive plastic foam), material which
interferes with the reflection of sound waves.
The minimum obtained is not zero (but very low, nevertheless) and the pressure minimum
just above the 5 dm abscissa: which coincides with the base of the cone of the loudspeaker
membrane.
Another example
It is also possible to select another frequency that will give another standing waves system.
From the relation N = (2k + 1) v/4L, we select for example k = 2, thus N = 865 Hz.
The recording is done under the same conditions and we obtain the following graph:
This time, the acquisition and modelling give a distribution as shown above, which is in
agreement with the theoretical study. The length of the tube is equal to l = 5./4.
The modelling parameters give a value of = 0.393 m, thus we deduce that the speed of
sound is v = N. = 865 x 0.393 = 340 m.s
value at 25°C.
ENGLISH
•
The result gives v = 519 x 0.662 = 343.6 m.s
the experiment's temperature - 25 °C – is 346 m.s
obtained is 0.7 %).
-1
(the theoretical speed of sound at
V
N
V
N
N
V
N
N
-1
, that is a theoretical difference of 1.8 % with the
24
-1
, the relative difference
N
V
V
V
V
N
V
V
N
N
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