Hans Christian Ørsted’s accidental discovery in 1820 was the observation that an electric current produces a magnetic field. Ørsted made this discovery during a lecture demonstration at the University of Copenhagen.

As the story goes, Ørsted was conducting an experiment involving an electric current passing through a wire. He had set up a simple circuit with a battery, a wire, and a compass needle. During the experiment, Ørsted noticed that when the electric current flowed through the wire, the nearby compass needle deflected from its usual north-south alignment.

This unexpected deflection of the compass needle was a crucial observation. It indicated that the electric current was somehow influencing the space around it, creating a magnetic field. Ørsted’s accidental discovery revealed the fundamental connection between electricity and magnetism, marking a significant milestone in the understanding of electromagnetism.

This discovery laid the groundwork for further exploration by scientists such as André-Marie Ampère and Michael Faraday, ultimately leading to the development of electromagnetism as a branch of physics and the subsequent technological advancements in electrical engineering.