Elenco Snaptricity&reg - Manual (Page 71)

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Make Your Own Electromagnet Project #61
Educational Corner:
The iron core rod may remain
magnetized for a while after you
turn off the circuit. Magnets are
usually made by subjecting iron
bars to powerful magnetic fields.
Some iron ores hold a
magnetization for a long time,
while other ores lose it as soon as
the magnetizing field is removed.
Heat and vibration can speed up
demagnetization.
FOR ADVANCED USERS - ADULT SUPERVISION RECOMMENDED
Rubber Grommet
Iron Core Rod
Part B
Electric Paths
This circuit shows how wrapping a wire into a coil concentrates the
magnetic field from the wire. The more loops of wire a coil has, the
stronger the magnetic field produced. So if you only loop the jumper
wire around the iron core rod a few times, the magnetic field will not
be nearly as strong. You can also see how looping the wire around
an iron core increases the magnetic field produced.
Description
Push the press switch (S2) and move the iron core rod (with the red
wire around it) around the compass and watch how it attracts the
compass needle. The lamps (L4) also light when the switch is pressed.
Flip both slide switches to reverse the current. Push the press switch
again and watch the compass to see how the magnetic field has changed.
Part B: Now take off the rubber grommet and remove the iron core
rod, but keep the red wire wound in a coil and connected to the
circuit. Push the press switch and watch the compass while moving
the coiled red wire around it. Now the compass needle has much
less attraction to the red wire.
Operation
Build the circuit. Place the rubber grommet on one end of the iron
core rod and wrap the red jumper wire tightly around it, as shown.
Connect the red jumper wire to the circuit. Set the slide switches
(S5) so both are in the same position (B or C).
Assembly
Snappy says:
Your electromagnet (M3) is
just like the coiled red wire
except that it has many
more loops. This gives it a
stronger magnetic field.