Compass used in Oersted’s original electromagnetism experiment, 1820

Replica produced in 1931. The Danish physicist Hans Christian Oersted (1777-1851), discovered electromagnetism (the interaction between electricity and magnetism) in 1820. In front of an audience of students, Oersted placed a compass needle directly beneath a wire, through which an electric current was passed, causing the needle to move. Oersted’s discovery sparked a surge in interest in electricity amongst European scientists.