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Les langues disponibles
Ultrasounds
Moduson table
Ref :
223 008
• Once the receiver has been installed, its displacement inside the arc-shaped recess will
• Select the distance a between the 2 transmitters (3 values are marked: a=2 cm, a=4 cm
4 Theoretical study of interference phenomena
Ultrasonic interference with MODUSON
For an arbitrary receiver position M, the difference in the courses of the ultrasonic waves
from of S
d
2
2
d
=hM
2
2
d
=hM
1
2
d
2
or δ=2 aDsin(θ)/(d
or else:
ENGLISH
produce a succession of peaks and minima having the amplitude of the signal sensed by
the receiver and observed on the oscilloscope screen.
This is the series of the antinodes and nodes corresponding to the constructive and
destructive interferences that appear in the vicinity of the two synchronous sources used.
and a=8 cm, but any other value from 2 to 4 cm can be measured by means of a 20-cm
rule) and the radius D of the receiver displacement arc (2 radii can be used: D=15 cm and
D=30 cm). The measurement of the angular X-axis values θ of the consecutive minima
(or peaks) yields the value i of the interfringe distance and allows the verification of its
expression versus a and D with a fairly good accuracy.
• Theoretical study
o The theoretical top-view diagram is as follows. The receiver M moves on the arc
of circle with radius O M
by a distance S
S
1
h
M
is δ= d
and S
- d
1
2
2
1
and d
are the hypotenuses of two rectangular triangles. The following can be expressed:
1
2
2
2
+hS
=Ov
+ (Oh+a/2)
2
2
2
2
+hS
=Ov
+ (Oh- a/2)
1
)= δ(d
2
- d
=(d
-d
)(d
+d
+d
1
2
1
2
1
2
+d
)
2
1
δ
=
2
a
+
+
2
D
4
λ
⋅
D
=
i
a
=D. The two synchronous sources S
0
=a
2
a
S
O
S
1
2
θ
d
d
1
2
D
v
M
0
2
2
2
=D
cos
(θ)+(Dsin(θ)+a/2)
2
2
2
=D
cos
(θ)+(Dsin(θ)- a/2)
)=2 aDsin(θ)
1
θ
2
aD
sin(
)
2
a
θ
+
+
2
aD
sin(
)
D
4
35
and S
1
2
2
2
=D
+a
/4+aDsin(θ)
2
2
2
=D
+a
/4- aDsin(θ)
θ
−
aD
sin(
)
are spaced
2
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