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Ultrasounds
®
Moduson
2 transmitter telemeter 12V
Ref : 222 082
3.2 Detecting ultrasound waves
The following experiment is performed on the desk. Bursts of ultrasound waves are emitted
by the transmitter E and received by the receiver R. To determine the distance d that
separates E from R, we study it on the oscilloscope:
The oscillogram 1 corresponds to E.
The oscillogram 2 corresponds to R.
The horizontal adjustment is 2 ms per division (one horizontal division is equal to a duration
of 2 ms.).
Draw the diagram of the experiment.
1. Find the velocity of propagation of sound or ultrasound waves in air.
2. What is the duration that separates the start of the transmission from the start of the
3. Calculate the distance d, then verify the result by measuring d with a graduated ruler.
Partial answer:
1.
2. v = 340 m/s
3. 0.77 ms; d = 26 cm; 25 cm with a graduated ruler (the distance of 1 cm between the
3.3 What happens when ultrasound waves encounter an
Write an experimental protocol that can be used to know what happens when ultrasound
waves encounter:
• A cardboard sheet
• A facial tissue paper
• A plastic character
• A hand.
The experiments are then performed on the desk by the teacher or the student. Note down
the results in the notebook.
Partial answer:
Place the screen in front of the transmitter; the receiver is placed opposite the screen.
Observe the oscillogram corresponding to the transmitter.
Results: A cardboard sheet, a plastic character or a hand reflect ultrasound waves; a facial
tissue paper (open the tissue and keep only one layer) reflects and transmits ultrasound
waves.
ENGLISH
reception?
Channel 1
sensitive tip and the E or R casing must be taken into consideration).
obstacle?
E
d
19
Channel 2
R
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