An alternating current (A.C.) generator is an important application of electromagnetic induction. A.C. generator is an electromagnetic device which transforms mechanical energy into electrical energy. It consists of a rectangular coil of wire which can be rotated about an axis. The coil is located between the poles of two permanent magnets. As the coil rotates, the magnetic field through the coil changes, which induces an electromotive force (e.m.f.) between the ends of the coil.
Note: The induced current does not flow UNLESS the generator is electrically connected to an external circuit with an electrical load, such as a light bulb as shown in the above figure.