Electromagnetism

Hans Christian Ørsted
Hans Christian Ørsted

At the beginning of the 19th century electricity and magnetism were thought to be separate phenomena. But in 1820 Hans Christian Ørsted discovered that an electric current affects the movement of a compass needle; this revealed that they are actually aspects of a single phenomenon that was given the name electromagnetism. This discovery soon led to inventions that gave physicists access to electric currents and high voltages that could be used in experiments.

During the 18th century researchers sought to understand the nature of electricity. They created static electricity that could be stored in capacitor plates or Leyden jars, and they demonstrated the existence of electric charges.

Voltas stack, also
called a galvanic cell

Theories arose about the existence of different kinds of electricity. When Luigi Galvani succeeded in making the leg muscles of frogs twitch by applying an electric spark, he concluded that there was a special kind of animal electricity. However, Alessandro Volta believed that there was only one kind of electricity. While working to prove this he invented the first electric battery, the voltaic pile, which became an important source of electrical current.

Geomagnetic studies
Within the field of magnetism, researchers studied the Earth’s magnetic field and the difference between magnetic north (indicated by a compass) and geographic north (defined by the Earth’s axis of rotation). By measuring variations in this difference, they gained an increased understanding about the interior of the Earth. Several Uppsala professors also conducted magnetic field studies in Swedish ore fields, which led to new discoveries of iron ore.

Electromagnetism paved the way for new experiments
Hans Christian Ørsted’s insight in 1820 that electricity and magnetism interacted as electromagnetism encouraged the development of theories about electrodynamics.
The discovery of electromagnetism led to important inventions such as electromagnets, electric generators and electric motors – the basis for today’s electrical technology in cars, mobile telephones and computers.


Alessandro Volta (1745–1827) contributes to the development of the electroscope and invents the voltaic pile, the first battery.
Christian Ørsted (1777–1851) discovers that a magnetic needle is affected by a conductor carrying electric current.
André-Marie Ampère (1775–1836) creates electrodynamics and introduces the term ”electric current”.
Michael Faraday (1791–1867) discovers how an electrical circuit may be closed or broken, switched on or off, using electromagnetic induction.
Hippolyte Pixii (1808–1835) constructs the first generator / dynamo that provides a larger electric current.
Carl Friederich Gauss (1777–1855) develops units of measurement for electricity and magnetism.
James Clerk Maxwell (1831–1879) summarizes important electromagnetic phenomena in equations that predict the existence of radio waves.
Robert Thalén (1827–1905 develops special instruments to study magnetic fields.
William Thomson, ennobled as Lord Kelvin (1824–1907) develops galvanometers that can measure electrical current.