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Unit 11: Magnetism Page 24
fingers. Remember that 1. Remove the insulation from
attached to this shaft is a coil of about an inch of each end of the
wire. When you spin the shaft, wire. (Use sandpaper if you're
you're also moving a coil of wire using magnet wire.)
past the permanent magnets
inside to motor, which will 2. Wrap the wire at least 30-50
create electricity in your coil and times around your fingers, making
out the terminals. sure your coil is large enough to
slide the compass through.
2. Attach a low-voltage bipolar LED
(RS #276-012) directly to the
3. Connect one end of the wire to
motor terminals. Bend the end
the battery case wire using an
of each ‘leg’ of the LED into little
alligator clip wire.
hooks and hook one to each
motor terminal. 4. While looking at the compass,
3. Spin the shaft to see the LED repeatedly tap the other end of the
light up. Depending on the size wire to the battery. You should see
of the magnets inside your the compass react to the tapping.
motor, you may need to spin
5. Switch the wires from one
the shaft super fast to see the
terminal of the battery to the
LED light up. The larger the
other. Now tap again. Do you see a
motor, the easier this activity
difference in the way the compass
is. Try using a 9-18VDC motor
moves?
(RS #276-256) from Radio
Shack.
You just made a simple
galvanometer. “Oh boy, that’s
Experiment:
great! Hey Bob, take a look! I just
Galvanometers
made a....a what?!?” I thought you
might ask that question. A
Galvanometers are coils of wire
galvanometer is a device that is
connected to a battery. When
used to find and measure electric
current flows through the wire, it
current. “But, it made a compass
creates a magnetic field. Since the
needle move...isn’t that a magnetic
wire is bundled up, it multiplies this
field, not electricity?” Ah, yes, but
electromagnetic effect to create a
hold on a minute. What is electric
simple electromagnet that you can
current...moving electrons. What
detect with your compass.
do moving electrons create...a
magnetic field! By the
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