Andre-Marie Ampere, French physicist and mathematician, early 19th century.
© Science Museum / Science & Society Picture Library
Engraved portrait of AndrE-Marie AmpEre (1775-1836). Hans Christian oersted's (1777-1851) discovery that an electric current generates a magnetic field stimulated Ampere to investigate electric current and electrodynamics. His most significant contribution was the mathematical formulation of magnetism, known as Ampere's law, which he provided in 1827. The SI (the international system of standard scientific units) unit of electric current was named in his honour in 1881, replacing the term 'weber'. Illustration from 'Die ElektricitAt im Dienste der Menschheit' (Electricity in the service of mankind) by Alfred Ritter von Urbanitzky (b 1852), published in Vienna in 1885.