Electromagnetism (EM): Research connections

In 1820, Hans Christian Oersted first observed a connection between electricity and magnetism by validating the torque on a compass needle triggered by adjacent electric current. His discovery was published in 1820 (without mathematical proof), entitled "Experiments on the Effect of a Current of Electricity on the Magnetic Needle." In the same year, extending Oersted’s experimental work, André-Marie Ampère given a mathematical law to explain the magnetic forces that originated between current-carrying wires. Ampère demonstrated that two parallel wires carrying electric currents attract or repel each other, depending on whether the currents flow in the same or opposite directions, respectively. Michael Faraday (in 1831) and Joseph Henry (in 1832) independently discovered EM induction, nearly a decade after the works of Oersted and Ampère. Faraday demonstrated that a changing magnetic field induces an electric current, and in 1864, James Clerk Maxwell proposed a comprehensive “Theory of Electromagnetism," formally unifying electricity and magnetism. He noticed that electrical fields and magnetic fields can couple together to form EM waves.