The principle of operation of the electric induction motor is essentially composed of a permanent magnet suspended by a wire on an aluminum or copper disk in a bearing on a fixed iron plate. The induced parasitic currents tend to produce a unitary pole S (south) on the disk at a point located under the magnet’s north (N) rotating pole, and a unit pole N on the disk under the magnet rotating pole S. The disc turns in the same direction as the magnet, but the speed must always be lower. If the disk were activated at the same magnet speed, there would be no relative motion between the conductor and the magnetic field and the induced current would be zero and no magnetic flux or torque would be given. Coxreels 112-3-100
The field of the permanent magnet is completed through the iron plate and the disk follows the movement of the magnet due to the induced parasitic currents that appear because of the relative movement of the conductor relative to the magnetic field. By Lenz’s law, the sense of induced voltage produces a field that tends to oppose force, that is, the motion that produced the induced voltage.