5K10.20 - Effect of a Magnetic Field on the Current in a Coil
Demonstrate that a moving magnet can cause a current in a coil.
Instructions The outer coil of the large pair of demonstration coils which fit one inside the other is connected to the zero center projection galvanometer. If the bar magnet mounted on a stick is passed through the coil, the meter will deflect in one direction and then the other. If the direction of the magnet is reversed, the direction of the initial deflection will reverse. If the magnet is brought up and then back, the direction of the deflection reverses. To emphasize reversibility, first hold the coil steady and move the magnet, and then hold the magnet steady and move the coil.
This can also be used to show the presence of the earth's magnetic field. Holding the coil so that its axis is vertical quickly rotate it to horizontal.