If the rotor is inserted in the middle of a rotating magnetic field, it will be induced because of the variation of magnetic flux, a magnetic field will manifest in the rotor, making it rotate when trying to follow the field of the stator.
Motors that operate according to the induction principle are classified as asynchronous motors because the rotor rotates at a slower speed than the synchrony.
The asynchronous motor works by induction by the rotating magnetic field, where a magnet in the form of a horseshoe is suspended by a wire on a disk of copper or aluminum, which, in turn, is on an iron plate. The function of this plate is to close the magnetic circuit, completing the path of the magnetic flux coming from the permanent magnet.
The function of the bearing and the pivot is to ensure that the disk can rotate freely and if the magnet begins to rotate, its magnetic field will also rotate. This movement will induce in the parasitic currents (generative action phenomena), which produce an induced magnetic field that opposes the movement of the magnet (Lenz’s law).
It can be said that the magnetic field of the parasite currents produces a south pole on the disk, near the north pole of the magnet, and a north pole on the disk near the south pole of the magnet.