Steve Reed, age 11, of Wichita, Kansas, for his question

Who invented the generator?

His name was Michael Faraday. His interest in science drew him to the Royal Institute in London, where he paid his tuition by cleaning up the labs. He was fascinated by the chemical battery, already invented by Volta, and he pondered the possibility of generating electric current by mechanical means. The story goes that he attended classes with pockets stuffed with bolts, magnets and bits of copper. In 1831, at the age of 40, Faraday discovered how to assemble similar items to build the first dynamo for generating electricity.

His first model was a flat horseshoe magnet with an upriht copper disk set to rotate between its prongs. When he turned a handcrank, the copper cut through the invisible lines of magnetic force, generating an electric current that was led through a circuit of copper wire. Our modern generators are enormous and either the copper or the magnet may be made to spin. But they work on the same principle as the first little dynamo invented by Michael Faraday, 139 years ago.