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Ultrasounds
®
Moduson
2 transmitter telemeter 12V
Ref : 222 082
3 Existence of points in phase and out of phase
This experiment is designed to show the existence of a same vibratory state at various
points in space, in the transmission zone of an ultrasound wave.
The experiment requires the entire device. The transmitter and the two receivers are placed
on rails: The transmitter in its slot on the left and the receivers A and B in the guide rails are
positioned using their pointers placed at the zero markings. Connect the transmitter to the
power supply and the receivers to the vertical inputs of a dual-trace oscilloscope (level on
each channel: 100 mV/div and time base: 5 µs/div). The On/Off button is placed in the On
position and the Continuous – Bursts reversing switch in Continuous.
Adjust the frequency-setting button of the transmitter to obtain maximum amplitude of signals
detected by the receiver on the oscilloscope screen.
After having rectified the zero position of one of the receivers if necessary, the two signals
detected have the shape on the oscilloscope screen as shown below: they can be
superimposed.
The points located on the sensors of the receivers are in the same vibratory state: they are in
phase.
We move the receiver A slowly to the right; the corresponding signal also moves to the right
of the screen and it is possible for multiple positions of A to obtain it in phase with the one
detected by B.
4 Verifying the relation = V/N
The previous experiment is followed by this one. It introduces the definition of wavelength:
distance separating two consecutive points vibrating in phase.
Move the receiver A while keeping B fixed. Measure the distance d separating A from B
when the signals on the screen are n times in a row in coincidence. We deduce
obtain a value close to 8.5 mm.
The known values of V and N result in the theoretical value of
the previous measurement.
ENGLISH
= V/N which is very close to
16
= d/n. We
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