Scott Ward, age 13, of Richmond, Va., for his question:
HOW DOES AN ELECTRIC GENERATOR WORK?
A generator may be small enough to hold in the palm of your hand, or it may be larger than your garage. The size of large generators is usually measured in kilowatts. One kilowatt equals 1,000 watts, the power needed to light ten 100 watt light bulbs. A giant generator can produce more than 1 million kilowatts of electricity. Electric generators were once called dynamos.
An electric generator is a machine that produces electricity.
A generator does not actually create energy. It changes mechanical energy into electrical energy. Every generator must be driven by a turbine, a diesel engine or some other machine that produces mechanical energy.
As an example, the generator in your family automobile is driven by the same engine that runs the car. Even windmills can drive generators.
Prime mover is a term used by engineers for the mechanical device that drives a generator. To obtain more electric energy from a generator, the prime mover must supply more mechanical energy.
If the prime mover is a steam turbine, more steam must flow through the turbine in order to produce more electricity.
An English physicist named Michael Faraday in 1831 discovered a principle which allows generators to produce electricity. He found that electricity could be produced in a coil of copper wire by moving the coil near a magnet or by moving a magnet near the coil.
A simple generator consists of a U shaped magnet and a single loop of wire. The area around the magnet where its force can be felt is called a magnetic field. The stronger the magnet, the greater the force.
If you rotate the loop of wire between the poles of the magnet, the two sides of the loop "cut" the lines of force. This induces, or generates, electricity in the loop.
The voltage a generator produces can be increased by increasing the strength of the magnetic field, the speed at which the loop rotates or the number of loops of wire that cut the magnetic field.
There are two main types of generators: direct current (d c) generators, which produce electric current that always flows in the same direction, and alternating current (a c) generators, which produce electric current that reverses direction many times every second.
Both a c and d c generators work on the same scientific principles. But each differs in the ways they are built and used.
Many a c generators rotate at speeds as high as 3,600 turns a minute. The high speeds produce heat which must be cooled by blowing air through the generator, or by running a cooling liquid or gas past the coils and iron cores.