FIG. 22.—A COIL WITH A CURRENT FLOWING THROUGH IT ACTS LIKE A MAGNET
The coil is picking up iron filings.
Ampère
The news of Oersted's discovery aroused great interest throughout Europe. Soon after its announcement in France, André Marie Ampère made a discovery of equal importance. Oersted had discovered electromagnetism. Ampère discovered electrical power or motion produced by an electrical current.
The youth of Ampère was passed amid the stormy scenes of the French Revolution. His father had moved from his country home to Lyons and become a justice of the peace. In the destruction of the city of Lyons during the Reign of Terror he lost his head under the guillotine.
The blow was too great for Ampère, then a youth of eighteen. He had been a precocious child, advanced beyond his years in all the studies of the schools. But now his strong mind failed. For a year he wandered about mechanically piling up heaps of sand or gazing upon the sky. Then his mental power returned, and he took up with eagerness the study of botany and poetry.
He became a professor in the Polytechnic School in Paris, and it was while teaching in this school that he made his great discoveries. He found that two coils of wire can be made to attract or repel each other by an electric current. If the current flows through the two coils in the same direction, they attract each other (Fig. 24). If the current flows in opposite directions through the coils, they repel each other (Fig. 25). This is not very strange to us, for we know that a coil with a current flowing through it acts just like a magnet. Each coil then has a north pole and a south pole. If the coils are placed so that the two north poles or the two south poles are together, they will repel each other. If the north pole of one coil is near the south pole of the other, they will attract each other.
