Evan Garrett, age 10, of Sarasota, Florida, for his question:

What does water have to do with electricity?

Electricity is generated when copper keeps slicing through the invisible force lines around a magnet. A generator needs something to spin around either its massive copper coils or its giant magnet. But spin it must. This is what sends the current through the power lines. And water, falling water, can do the job. It may be a natural waterfall or a man made waterfall from a dam.

In olden days they set a big wheel straight up with part of its rim in a rushing stream. The force of the water pushed the wheel around and the wheel turned stones to grind grain into flour. On a grand scale, a generator that uses falling water is an up to date version of the waterwheel by the old mill stream. The falling water spins the turbines that generate the electricity through the power lines. This sort of power plant burns none of those fossil fuels that pollute the earth.