Oersted

Hans Christian Ørsted (1777–1851) was a Danish physicist and chemist, whose name is associated with a pivotal discovery in the history of science. Born in Rudkøbing, he studied at the University of Copenhagen and later became a professor of physics there, contributing to teaching and research across several decades.

In 1820, Ørsted conducted experiments that demonstrated a direct link between electricity and magnetism. He observed that a compass needle deflected when placed near a wire carrying an electric current, showing that electric currents produce magnetic fields. This crucial finding established the relationship between electricity and magnetism and helped stimulate the development of electromagnetic theory, influencing subsequent work by scientists such as Ampère and Faraday and contributing to the eventual formulation of Maxwell’s equations.

The oersted, symbol Oe, is a unit named in Ørsted’s honor. It is a unit of magnetic field strength defined in the centimeter-gram-second (CGS) system of units. In SI terms, 1 Oe is equivalent to about 79.58 amperes per meter. While the oersted has largely been superseded by SI units, it remains encountered in historical contexts and older literature on magnetism.

Ørsted’s discovery had a lasting impact on science and technology, underpinning the fields of electrodynamics and the design of electric motors and generators. He continued his scientific work in physics and chemistry until his death in Copenhagen in 1851.