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Electromagnetism
Reversible demonstration alternator
Réf :
292 075
ENGLISH
1.4
Use
The alternator is positioned in one
direction, and the upper plate to which
the two magnets are fixed is free to
rotate relative to the coil.
The upper plate is rotated:
-
either by pushing one of the four stops fixed to this plate with your finger,
and holding the lower plate fixed.
-
or by moving this plate uniformly, using a pen located in the orifice provided
for this purpose.
1.5 Technical characteristics
The device is made from transparent polycarbonate. The two coaxial plates
are mounted on a ball bearing.
The coil inductance is 650 mH and the magnets are made of ferrite.
The coil ends are fixed to two pairs of
pitch of 38 mm compatible with UME dipoles.
The two pairs of bushings in parallel can be used to connect a dipole (for
example a LED) to the coil so that it is always visible regardless of the position
of the reversible rotating alternator (see images above).
2 Usage
2.1
Production of a variable voltage
2.1.1 Demonstrating the alternating nature of the voltage
produced
The alternator is positioned so as to
rotate the magnets.
A LED is connected to the coil
terminals.
The magnets are rotated relative to
the coil, either by pushing them or
using a pen located in the orifice of
the upper plate.
If the rotation speed is sufficient, it will
be seen that the LED flashes. The
LED is special in that it only lights up when current passes through it in one
direction, consequently it can be concluded that rotating magnets relative to
the coil generates an alternating voltage at the coil terminals that only
generates a current during one alternation (the LED lights up).
12
The alternator is positioned in the
other direction, the upper plate to
which the coil is fixed is free to
rotate relative to the magnets.
ø
4 mm safety bushings in parallel at a
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