When the switch is closed, a magnetic field is produced in the coil on the top part of the iron ring and transmitted to the coil on the bottom part of the ring. It is the change in magnetic field that...When the switch is closed, a magnetic field is produced in the coil on the top part of the iron ring and transmitted to the coil on the bottom part of the ring. It is the change in magnetic field that creates the current in the following way: a changing magnetic field induces an electric field, which results in the induced voltage. The faster the motion, the greater the voltage, and there is no voltage when the magnet is stationary relative to the coil.
