Discovery of electromagnetism by Hans Christian Ørsted (1777-1851) in 1820 - stock illustration

The Danish physicist and chemist Hans Christian Ørsted (1777 - 1851) discovered that electric currents create magnetic fields. On 21 April 1820, during a lecture, Ørsted noticed a compass needle deflected from magnetic north when an electric current from a battery was switched on and off, confirming a direct relationship between electricity and magnetism. (top and bottom, left)The galvanometer - an electromechanical instrument - developed later from this observation (bottom, right). Wood engravings, published in 1885.