the 1820sReputable sourceWell documented
Oersted, Ampère, and Electromagnetism
On the timeline · around the 1820s ·
What happened
In 1820 the Danish scientist Hans Christian Oersted noticed that a compass needle twitched near a wire carrying an electric current — the first proof that electricity and magnetism are linked. Within weeks the French physicist André-Marie Ampère worked out the mathematical laws of the forces between currents, founding the science he named 'electrodynamics.'
Why it matters
The discovery that electric currents create magnetism united two forces long thought separate and launched the study of electromagnetism. The unit of electric current, the ampere, honours Ampère's pioneering work.