A large demo coil is connected to a galvanometer which can be projected on the screen. If a bar magnet is now moved into the coil, the meter will deflect in one direction. When the magnet is moved away, the meter will deflect in the opposite direction. If the direction of the magnet is reversed, the initial deflection will reverse. If the magnet is held in place, the deflection will return to zero.
A second coil, connected to DC power supply and a momentary switch, may be placed close to the first coil. When you close the switch, the meter will deflect in one direction, returning to zero. Opening the switch will cause it to deflect in the opposite direction.