3B SCIENTIFIC PHYSICS U8493600-230 Mode D'emploi page 11

6.7 Huygens' principle
•
Set up the transmitter (11) about 20 cm from
the plate holder and the receiver (19) about 80
cm behind the late holder on the rails.
•
Turn the receiver around on its rail so that it is
out of the bundled microwave beam and the
signal is clearly weakened.
•
Insert a single slit aperture into the plate
holder and secure it gently in place (line up the
centre of the slit in the centre of the plate).
Conclusion: microwaves are diffracted by the slit
and wavelets can be detected beyond the plate (the
modulation signal is audibly louder).
6.8 Diffraction
•
Clamp the cover plate (15) in the holder on the
hinge plate.
•
Set up the transmitter about 20 cm in front of
the plate.
•
Move the probe (21) in a horizontal plane be-
hind the plate.
Conclusion: even when the probe is in the shadow
of the plate, it can still pick up signals due to dif-
fraction.
6.9 Interference
•
Clamp the plate with the double slit (16) cen-
trally in the holder on the plate over the hinge.
•
Position the transmitter about 12 cm in front
of the plate.
•
Move the receiver probe parallel to the plate
with the double slit about 6 cm behind it.
Conclusion: Since the number of maxima is larger
than the number of slits, this demonstrates the
presence of interference.
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