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Unit 11: Magnetism Page 19
almost all electrical production create an electric current in that
comes from something huge metal.
spinning really fast!
Magnetism can create electricity
In this unit, we’re going to make and electricity can create
several really fun gadgets that rely magnetism. Now, let’s go way back
on this ‘electricity makes in time and try to remember the
magnetism’ and ‘magnetism makes work we did with sound in Unit 6.
electricity’ thing. You’ll be able to Sound is vibrations. If something
baffle most grown-ups with these vibrates between a frequency of
creations! 20-20,000 Hz our ears can detect
it as sound.
How magnets make sound
To make a speaker, we need to
We’ve come a somehow make something vibrate.
long way with “Hmmm, I wonder if this
this magnetism magnetism/electricity could
thing and somehow be useful here.”
hopefully
you’re feeling So what’s going on with a speaker?
pretty good What makes it work? Okay, here’s
about how magnetism works and the deal. The radio provides the
what it does. Now we’re going to electricity that gets pumped
use what we’ve learned to make through the wires. The radio very
simple versions of two gadgets that quickly pumps electricity in one
you use every day. direction and then switches to
pump it in the other direction. This
Let’s start with the slightly simpler movement of electrons back and
gadget. Now to understand what’s forth creates a magnetic field in
happening here, we need to recap: the coil of wire.
Remember, that electricity is
moving electrons and what do Since the electricity keeps
moving electrons create? A reversing, the magnetic field keeps
magnetic field. reversing. Basically, the poles on
the electromagnet formed by the
Also, remember that a magnetic coil go from north to south and
field, when moved near a metal back again. Since the poles keep
that can conduct electricity, will reversing, the permanent magnet
you have taped to the cup keeps
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