Donna Holmerv age 12, of La Mesa, CA

How do we get electric power from water?

With a hiss and a spatter, a drop of water can put out a candle, Damp kindling refuses to burn and the fireman’s weapon against a blaze is a jet of water. We all know that water fights fire. Yet we are told that water is used to power our steady electric lights. This is true. Water is even used to power the electric stove and electric heater. Of course, we know that this water is used to generate electricity at the power house. It is very, very dangerous to mix water and electric wiring and no sensible person would think of doing it,

The water used to generate electricity is always falling water. It may be borrowed from the teeming cataract of Niagara or from the giant spillways of Hoover Dam. This is because it must be working water. Falling water has a great deal of force. You know this from the shower bath,

At the power plant, this falling water is used to turn wheels. People have been using water wheels for thousands of years, Some water wheels have rims with slats, others have rims fitted with little buckets. Part of the rim touches the falling or flowing water. The wheel is pushed around by the moving water. The pressure may move the slats and they in turn move the wheel. Or, as the little pails fill with water the wheel is pulled around by their weight. They are fixed to empty themselves when they turn over the top of the wheel,

These old time waterwheels were often used to turn the mill stones for grinding flour. The modern waterwheel that works ant electric generator turns magnets or copper coils. For the electricity that lights our homes is generated from magnetism and moving copper,

You may know something about magnetism from playing with a toy magnet. The magic pulling force reaches out beyond the metal magnet. Even a small magnet can pull pins towards itself from quite a distance and hug them tight,

Magnetism has an especially powerful effect on copper. It happens when copper is moved through magnetic field, which is the area of force that reaches out beyond the metal of the magnet, Trillions of little electrons are agitated, Under certain conditions they can be forced to march along in the same direction. It is these countless electrons, marching together, that give us the current to light our electric lamps.

The first dynamo was a copper disc, hand turned through the magnetic field between the two ends of a horseshoe magnet. A circuit of copper wire looped from one end of the magnet to the other. An electric current ran through the wire so long as someone turned the 'handle that moved the copper disc through the magnetic field.

Since then. we have persuaded falling water to do that turning job for us, Huge cataracts are needed to turn the massive magnets or the colossal copper coils in a giant generator, For the more magnetism and the more copper, the more electric current we get. In some generators, it is the electromagnet that swings with lighting speed around the copper coils. In others it is the copper coils that swirl around to cut through the magnetic field. In either case, the job of moving is done by falling water. We do not have to have falling water to generate electricity„ Some generators are turned by steam, Falling water just happens to be the steadiest, the cheapest and the most reliable moving force for generating electricity.