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Ultrasounds
Moduson table
Ref :
223 008
Determine the minimum variation of the angle for which the amplitude observed on the
oscilloscope screen is the highest.
Observe that this value is about 5 degrees.
Therefore the determination of the amplitude peak is rather inaccurate.
Conclusion :
We find that ultrasonic waves are rather directive (however much less so than light waves!)
The ultrasonic transmission zone (assuming that it is symmetrical about the transmitter axis),
for an amplitude value decreased by half its maximum value, is a cone having an angle close
to 60 degrees (angle aOb on the diagram).
Note: The experiment can be repeated by using the second recess for the receiver displacement.
1.3 Step 3: Exploitation of the results
Notion of sound direction or « sound radiation »:
The so-called « sound radiation » is the direction of transmission that corresponds to the
amplitude peak of the signal received by the receiver.
Representation of sound radiation
This radiation is represented by an oriented line with an arrow pointing outwards from the
transmitter. Its direction blends with the geometrical axis of the transmitter.
ER represents the sound radiation
2 Reflection of ultrasonic waves
Introduction: The purpose of the experiment is to verify the law of reflection. The influence
of the absorption phenomenon on the ultrasonic waves can also be observed.
2.1 Step 1: Setup
The system is set up as follows:
The reflective plane (mirror) fitted with a magnetic sole is positioned at the centre of the arc-
shaped recesses. An ultrasonic transmitter and a receiver are positioned as shown on the
diagram. The MODUSON main transmitter can be used directly but its base is too large and
does not fit into the recess in the moulded PVC table. It is preferable to use the
complementary transmitter 2, which has a suitable size, at the expense of a slightly bulkier
setup. The transmitter 2 is positioned e.g. on the 30 deg. graduation on the left.
ENGLISH
Approximation of the measurement :
15 V
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