The proper rotation of electric motors is the basis of many current appliances and sometimes this rotation is evident, as in fans or cakes, but sometimes remains somewhat hidden, as in the washing machine agitators or in the windows electric machines of some automobiles. To understand the operation of the motor we need some basic knowledge about electromagnetism, such as magnets, magnetic forces between magnets, magnetic fields acting on currents. The motor rotor requires a torque to start its rotation. This torque is usually produced by magnetic forces developed between the magnetic rotor poles and those of the stator (fixed part).

Attraction or repulsion forces produced between stator and rotor “pull” or “push” the movable rotor poles producing torques, which cause the rotor to rotate rapidly, until the frictions or loads attached to the shaft decrease the resulting torque to the value ‘zero’. After this point, the rotor rotates with a stable angular velocity. Both the rotor and the stator of the motor must be ‘magnetic’ because they are precisely those forces between poles that produce the torque needed to make the rotor rotate.