Bipolar electric motor

A bipolar electric motor is an electric motor with only two (hence bi-) poles to its stationary field. They are an example of the simple brushed DC motor, with a commutator. This field may be generated by either a permanent magnet or a field coil.

The 'bipolar' term refers to the stationary field of the motor, not the rotor. The rotors often have more than two poles, three for a simple motor and potentially more for a high-power motor. A two-pole rotor has the disadvantage that it is not self-starting in all positions and so requires to be flicked to start.