Stripped-Down Motor
In this activity, you’ll make an electric motor—a simple version of the electric
motors found in toys, tools, and appliances everywhere.
What Do I Need?
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aluminum foil
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scissors
paper clips (larger is better)
paper, plastic, or foam cup
masking tape
magnets (two or more, available at
Radio Shack)
copper wire (bare or coated)
sandpaper
battery (D or C cell)
permanent marker (any color is fine)
What Do I Do?
Building the Stand
1.Tear off two narrow sheets of
aluminum foil. These will connect
the motor to the battery.
other piece of foil and paper clip.
4.Place the paper cup upside-down
on the table. Tape the foil-covered
2.Take a paper clip and bend the
outside wire down, so that you
have a loop with post. Repeat with
another paper clip.
3.Wrap one end of the aluminum
foil around the long post of the
paper clip. Make sure there is
good contact between the paper
clip and the foil. Repeat with the
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end of one paper clip to the top of
Turn over the cup and drop
the inverted paper cup. Tape the
another magnet inside. The two
other paper clip to the opposite
magnets will stick together.
side.
5.Place a magnet on the top of the
cup, between the paper clips.
6.Put the cup back on the table
upside-down. This is the base for
your motor.
Making the Coil
1.Cut a length of about 2 feet (60
cm) of copper wire.
2.If the wire is coated, use the
sandpaper to scrape away about
an inch (2 cm) of the coating on
either end of the wire.
3.Wrap the coated part of the wire
around the battery to make a coil,
then remove the coil from the
battery.
wire with two bare ends sticking
out from either side.
5.Balance the coil between two
fingers and see if it spins easily. If
it is too off-balanced to spin
smoothly, adjust it.
6.Use the permanent marker to
mark one side of one end of bare
wire.
7.Rest the ends of the coil in the
cradles formed by the two paper
clips.
8.Adjust the height of the paper
clips so that when the coil spins,
it just clears the top magnet.
9.Connect the battery by pressing
the two free ends of the aluminum
4.Poke the bare ends of the wire
into and around the coil several
times to fix the coil in place. You
should now have a loop of coated
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foil pieces against either end of
the battery.
10. Give the coil a spin to start the
motor turning.
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Note: If the coil won’t spin, check that the coil is well balanced, that the coating
has been thoroughly scraped off the ends, that the one end has been marked on
one side with the marker, and that the coil and magnet are close but not touching.
Keep adjusting if necessary—it will work.
What’s Going On?
Electricity flows through the coil of wire and creates an electromagnet. One
face of the coil becomes a north pole, the other a south pole. The permanent
magnet below attracts its opposite pole on the coil and repels its like pole, causing
the coil to spin.
Another way to explain this is the motor effect: when electricity moves through
a wire in a magnetic field, a force results that moves the wire.
Why is it important to color half of one projecting wire with a marker? By
marking half of one end, you insulate the wire and prevent electricity from
flowing through it for half of each spin. This turns off the electromagnet for that
half spin, allowing momentum to carry it through to the next cycle. If you allowed
the electricity to flow continually, one pole of the electromagnetic coil would just
be continually attracted to the permanent magnet, and the coil wouldn’t spin.
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