Robert M. Bray, age 11, of Allentown, Pennsylvania, for his question:
How do they make electric power?
They make, or generate, electricity by inducing electrons to move through a wire circuit. This voltage pressure organizes zillions of electrons. Their motions provide the energy of the electric current in the wires. The secret of the generator lies in the fact that electricity and magnetism are related. As it spins, it spins copper coils through the force lines of a magnetic field.
Someday scientists will understand the mysterious relationships between electricity and magnetism. But for a long time we have known how to use them to generate electric current. We know how to transport its power long distances and how to tap its energy along the way. The king pin of the power system is a spinning generator It generates the voltage pressure that sends the electric currents through a continuous wire circuit. Electrical wiring is double because two wires are needed to conduct the unbroken circuit to and from the generator.
The generator itself is rather simple. It has only two major parts, though one of them must move continuously to make things happen. It needs a copper part and a magnet. A small model may use a simple horseshoe magnet, a large model may use a mighty electromagnet. In both cases, the solid magnet is surrounded by an invisible force field, with lines of magnetic energy looping between its two opposite poles. A small model may use a simple copper disk, set at right angles between the prongs of the horse¬shoe. A big generator may use a massive arm of copper coils.
The two ends of the wire circuit are attached to the unit, waiting for the voltage pressure to generate the current. But if the two parts of the generator just sit still, nothing happens. One of them must move so that the copper continuously cuts through and through the force lines of the magnetic field. In some mysterious way, this continuous slicing generates voltage pressure. The voltage organizes and pushes electrons throughout the circuit and the energy of their motion is the electric current.
In a small model, the copper disk can be attached to a hand crank and turned through the magnetic field. A large generator may be set up to spin its massive copper arm through its mighty magnetic field. Or its magnet may swing around, carrying its lines of force through the copper. In any case, a large generator needs more outside help than a hand crank to keep it spinning.
This outside energy may be provided from several different sources. The strength of falling water may be linked up to turn a generator. Some generators use the energy of steam, expanding from water boiled by coal or oil furnaces. In an atomic power plant, some of the heat from nuclear fission is used to boil water and the steam piped off to spin the generators.