Compas used in oersted's original electromagnetism experiment, 1820.
© Science Museum / Science & Society Picture Library
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 compas needle directly beneath a wire, through which an electric current was pased, causing the needle to move. oersted's discovery sparked a surge in interest in electricity amongst European scientists.