See how AC current shakes with a
- A strong magnet.
If you have one, a nice big refrigerator magnet will
work...or...Most hardware stores carry ceramic magnets that
you can buy for a buck or two.
-A light bulb.
bulb that has the filament (the wire that glows) closer to
the glass walls works best. Elongated bulbs like decorative
bulbs or ones that are used in appliances work well.
While the bulb is turned on, hold the magnet
next to the bulb. Watch what happens to the filament.
Food for Thought:
You should have seen the filament inside the
bulb shake and wiggle?
Electricity from your wall socket alternates direction
which's why the electricity in your house is called
alternating current or AC. Electricity flows one direction
then switches and flows the opposite way. This switching
back and forth happens 120 times a second or goes through 60
cycles each second (a cycle is one episode of back and forth
A wire carrying electricity creates a magnetic field. If
the direction of the electricity changes so does the
magnetic field. The wire or filament inside the bulb does
this. The hot glowing wire creates an alternating magnetic
Two magnets held near each other attract or repel each
other. By holding your magnet near the bulb the filament
inside the bulb gets attracted and repelled by the magnet
120 times a second. This causes the filament to wiggle and
you can see this!
If you have access to an overhead projector, place the bulb
on it with the projector turned off. You can see the shaking
filament projected onto a screen.
(This option was passed along to us after
seeing presenter extraordinaire, Al Gunther at NSTA
Copyright 1999 Do