THE ELECTRIC GENERATOR

An electric generator is constructed somewhat like a conventional motor, although it functions in the opposite sense. Some generators also can operate as motors; they are called motor/generators. Generators, like motors, are energy transducers of a special sort.
A typical generator produces ac when a coil is rotated rapidly in a strong magnetic field. The magnetic field can be provided by a pair of permanent magnets (Fig. 1). The rotating shaft is driven by a gasoline-powered motor, a turbine, or some other source of mechanical energy. A commutator can be used with a generator to produce pulsating dc output, which can be filtered to obtain pure dc for use with precision equipment.

Fig. 1. A simple type of ac generator.