Electromagnetism

The year 1820 marked a milestone in the unification of electricity and magnetism, which up to then had been considered as two independent subjects. The discoveries of Oersted and Coulomb provided the first clues that not only are electricity and magnetism interlinked in a complex and fascinating way, but they are basically two manifestations of the same phenomenon of nature. The laws of electromagnetism are subtle and complicated, and the representation of electric and magnetic lines of force paints a picture which illustrates the phenomenon.

Invention of the electric motor

On the practical side, it soon became apparent that the newly discovered laws point to a method for turning electrical energy into mechanical energy of motion. Electric currents make magnetic fields. When an electric current flows through a magnetic field, the charge carriers are subjected to a force. These two facts provide a link between currents and forces. With some mechanical ingenuity it became possible to design electric motors, using electrical energy to drive mechanical systems. The first such motor was built by Thomas Davenport (1802-1851) and Orange Smalley (1812-1893) at a blacksmith's shop in Vermont, New York. In 1834 they succeeded in producing rotary motion using current from a battery, and an electromagnet powered by the same battery. In other words, the same current which produced the magnetic field was subsequently acted upon by its own magnetic field!

At that time the generation for mechanical power from electricity did not seem important. This world-changing invention was not yet a commercial success.

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