(1777-1851) Danish Experimental Physicist (Classical Electromagnetism), Physical Chemist
Hans Christian 0rsted exhilarated the European scientific community in July 1820 with the announcement of his discovery that an electric current produces a magnetic field. Physicists, among them andre-marie ampere, lost no time following up on 0rsted’s groundbreaking work, developing the fields of electromagnetism and electrodynamics.
The man who would initiate the main thrust of 19th-century physics was educated as a pharmacist. At the age of 17, he moved to Copenhagen from Rudk0bing, Langeland, Denmark, where he had been born on August 14, 1777. His studies at the University of Copenhagen represented his first experience of formal education. He entered the university in 1794, earned a doctorate in pharmacology in three years, and settled down to practice his profession. But two years later he abandoned pharmaceutical work for an extensive tour of Europe. When he returned, he began to exercise his talent as a teacher, successfully offering a series of public lectures. 0rsted lived in an age in which specialization was far less developed than in our own, and when it was common for scientists to teach and do research in more than one field. In 1806, presumably on the strength of his teaching abilities, he became a professor of physics at the University of Copenhagen, a position he would retain until 1829.
In the late 18th century, interest in magnetism was spurred, in part, by the need for a compass that would be accurate near the polar regions and could thus be used in the search for the Northwest Passage (a sea passage through the Arctic regions of North America that would connect the Atlantic and Pacific Oceans). 0rsted began seeking the connection between electricity and magnetism around 1813, philosophically convinced that all forces in nature have a unified essence and can therefore be converted into one another. As early as 1600, William Gilbert, a pioneer of magnetism, had proposed such a connection. In 0rsted’s time, many physicists looked for a magnetic force acting in the direction of the electric current but failed to find it. 0rsted succeeded because he hypothesized that the magnetic force would be acting in a direction perpendicular to that of the current.
0rsted performed his history-making experiment before a lecture hall filled with his students, in April 1820. The demonstration was a simple one: he placed a compass needle beneath a wire connected to a battery. The needle moved faintly toward the wire. 0rsted was convinced of his success but, given the small size of the effect, proceeded cautiously. Not until July, after performing further experiments showing that a circular magnetic force, which aligns itself perpendicular to the current, is produced around the wire, did he report his findings to Europe’s leading scientific journals. Here at last was definite experimental evidence of the relationship between electricity and magnetism. Within weeks of learning of 0rsted’s results, Ampere in France would develop a mathematical description of the magnetic force between two electric currents, founding the new science of electrodynamics. The race to develop a unified theory of electrodynamics was on, although 0rsted himself would play no further role in it.
In 1829, he left his university post to become director of the Polytechnic Institute in Copenhagen, where he remained until his death on March 2, 1851. As a teacher and writer, he played a dynamic role in elevating the level of scientific education and research in Denmark. In 1824, he founded a society devoted to the spread of scientific knowledge among the general public, the Danish Society for the Promotion of Natural Science. His name was given to the oersted (symbol Oe), the unit of magnetic-field strength in the centimeter-gram-second system of physical units.
