The operation of electric motors is based on the principles of electromagnetism. The magnetic field is the region around a magnet Gates BX123 Tri-Power Belts , where a magnetic force of attraction or repulsion occurs. The magnetic flux is defined with the amount of field lines that reach perpendicularly a given area. Magnetic permeability measures the ease with which field lines can traverse a given material. Magnetic reluctance is the measure of the opposition that a medium provides to the establishment and concentration of magnetic field lines. The electromagnetic force arises when a conductor traversed by electric current is inside a magnetic field.

The characteristics of the lines of the magnetic field will always be closed lines, they leave and return to the same point and never cross, outside the magnet, the lines leave the north pole and they go towards the south pole and inside the magnet, the lines are oriented from the South Pole to the North Pole. They exit and enter the direction perpendicular to the poles surfaces, at the poles the concentration of lines is greater and the greater the concentration of lines, the more intense the magnetic field in a given region.