Your local utility delivers electricity to your home, but where
does the utility company get the electricity? They make it in a
generating plant by changing mechanical energy (motion) into electrical
energy. Giant coils of wire are moved past powerful magnets—then
presto! The pull of the magnets causes the electrons in the metal
wire to move. It’s not magic. It’s electromagnetic
In this activity, you’ll use a stack of magnets to generate
current in a wire. You’ll use a homemade galvanometer (a compass
wrapped in wire) to detect the current.
|Every generating plant needs a source of energy
to make the turbine blades spin and move the wire coils. Many
different sources of energy can be used to make turbine blades
move, including falling water from a dam; tidal action; burning
fossil fuels, such as natural gas; nuclear reaction; geothermal
power; solar power; and wind.
- 1 compass
- 1 iron nail
- 1 pkg. ring magnets, stacked together
- 2 pcs. 18-22 gauge wire, each 1.5 meters long with ends stripped
- 1 D battery
- electrical tape
- wire cutters
Set up the equipment as shown, but do not connect the wires
yet. Tightly wrap the iron nail in as many coils as will fit
in a single layer, leaving approximately the same amount of
wire free at each end. Set the wrapped nail aside.
Next, using the middle of the remaining piece of wire, wrap
the compass in four coils of wire, leaving the long ends free.
Make sure the coils are parallel with the compass needle. This
is your galvanometer. A galvanometer is a device
used to detect and measure current.
Tape the compass to a flat surface, and make sure the needle
can spin freely. Be sure the nail and the compass (galvanometer)
are at least 1 meter apart throughout the entire experiment.
(This is important, because you don’t want the magnets
to affect the magnetic compass needle.)
- Touch the ends of the galvanometer wire to the positive and
negative ends of the D battery. What happens to the needle in
your galvanometer? What caused this?
Is the current produced by the battery AC or DC? (Hint: Note
how the needle in your galvanometer moved.)
Set the battery aside. Now connect the ends of the galvanometer
wire to the ends of the wire wrapped around the nail. (Remember
to keep the nail and the galvanometer 1 meter apart.) Move
the stack of magnets back and forth over the nail. What happens
to the needle in your galvanometer? What can you conclude from
Did you produce AC current or DC current when you moved the
magnet back and forth over the coils?
- What do you think would happen if you used a stronger magnet?
More magnets? More coils of wire? Try it and see.
Electricity travels through some materials better
than others. Try this game to learn more.
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