Principle

Alternators work on exactly the same principle of electromagnetic induction developed throughout this unit: relative motion between a conductor and a magnetic field changes the magnetic flux linked with the conductor, and this changing flux induces an emf, whose magnitude is given by Faraday's law of electromagnetic induction and whose direction is given by Fleming's right hand rule. In a practical alternator, this relative motion is supplied continuously and indefinitely by mechanically rotating either the armature coil or the field magnet, which is exactly how a steady, continuously alternating emf (rather than a single moment …