Iron Core Rod
Rubber Grommet
Project 47
Electronic Magnet
Build the circuit shown. Place the iron core rod inside the
electromagnet (M3) and secure it with the rubber grommet.
This project works best if you have new alkaline batteries.
Hold the electromagnet near something made of iron and
push the switch (S2). While pressed, the electromagnet
will attract small metal parts like nails or will stick to a ham-
mer or refrigerator. Release the switch and the attraction
disappears.
Pressing the switch turns on an electric cur-
rent which transforms the electromagnet from
an ordinary coil of copper wire into a magnet.
An electronic magnet is much better than an
ordinary magnet because you can turn it on
or off with a switch!
An electron current flowing in a wire has a tiny
magnetic field. By looping a long wire into a
coil the tiny magnetic field is concentrated into
a large one. The strength of the magnetic field
depends on how much current is flowing in
the wire and how many loops of wire.
Names some advantages and disadvantages of electronic
magnets compared to permanent magnets.
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