The Standard Electrical Dictionary

1. Unipolar Current Induction

   Current induction produced by moving a conductor through a magnetic field of force so that it always cuts the lines in similar relation to itself. Thus it produces a constant current through its own circuit, if a closed one, and no commutator is required. As this case always in practice amounts to the cutting of lines of force in the neighborhood of a single pole the term unipolar is employed to designate the action. The simplest representation of unipolar induction is the rotating of a conductor around the end of a bar magnet, its axis of rotation corresponding with the axis of the magnet.