Content for Unipolar Motor

A unipolar motor (also called homopolar motor) is a direct current (DC) motor typically with slip-rings on each end of a cylindrical rotor and field magnets or a DC field winding generating a magnetic field on the stator. The rotor has typically not a winding but just straight connections in axial direction between the slip-rings (e.g. a copper tube encasing the rotor or rods embedded in the rotor). The field is uniformly perpendicular to the cylindrical rotor surface and does not change polarity over the 360-degree perimeter of the cylindrical part of the rotor. That means if the field is considered entering the rotor between the slip-rings it must leave the rotor though the rotor's end surfaces. It is not important that the magnetic field is generated from the stator; a similar field may be generated from the rotor with the same effect (the magnetic fields would not rotate with the rotor).