Hans Christian Ørsted

It’s the birthday of Hans Christian Ørsted, who was born in 1777 in Rudkøbing, Denmark. Ørsted studied physics and philosophy at the University of Copenhagen. His interest in electricity and his philosophical belief in the underlying unity of natural phenomena led him to investigate the connection between electricity and magnetism. In April 1820 he made the chance observation that a compass needle is deflected when a nearby current is switched on and off. Having observed a relationship between electricity and magnetism, he then set out to investigate it further. By July, he had discovered that an electric current produces a circular magnetic field. The symmetry of the magnetic field surprised Ørsted. In his 1820 paper he wrote, “The agreement of this law with nature will be better seen by the repetition of experiments than by a long explanation.”

Date in History: 14 August 1777