Title: Generating Electricity
Objective: When a magnet moves past a coil of wire, a current flows through the wire.
Purpose: To show that changing or moving magnetic fields can induce currents in
electric conductors.
Supplies: One coil of copper wire, one good bar magnet, and a accurate current meter.
Procedure: Connect the two ends of the coil of wire to the two terminals of the current
meter. Now move one pole of the bar magnet past the coil. You'll observe that the meter
needle moves first one way and then the other. Show that as the pole approaches the coil,
the needle moves one way and as the pole moves away from the coil, the needle moves
the other way. Try reversing the magnet (use its other pole)—the effect will reverse.
Science Behind It: The changing magnetic field through the coil produces an electric
field around it and this electric field pushes charges through the coil's windings. The
meter registers this flowing current. The direction of current flow is determined by the
direction in which the electric field points and that direction depends on how the
magnetic field is changing.