Faraday hoped that the magnetic field of the electromagnet would make—or induce—an electric current in the second wire. But no matter how strong the electromagnet was, he could not make an electric current in the second wire.
Success for an Instant
As Faraday experimented with the electromagnetic ring, he noticed something interesting. At the instant he connected the wires to the battery, the galvanometer pointer moved. This movement showed that an electric current was present. The pointer moved again at the instant he disconnected the battery. But as long as the battery was fully connected, the galvanometer measured no electric current.
Faraday realized that electric current in the second wire was made only when the magnetic field was changing. The magnetic field changed as the battery was connected and disconnected. The process by which an electric current is made by changing a magnetic field is called electromagnetic induction. Faraday did many more experiments in this area.
Inducing Electric Current
Faraday’s experiments also showed that moving either the magnet or the wire changes the magnetic field around the wire. So, an electric current is made when a magnet moves in a coil of wire or when a wire moves between the poles of a magnet.
Electromagnetic induction is very important for the generation of electrical energy. An electric generator uses electromagnetic induction to change mechanical energy into electrical energy.
Because the electric current changes direction, it is an alternating current. Generators in power plants also make alternating current. But generators in power plants are very large. They have many coils of wire instead of just one. In…