Photogravure after a stipple engraving of 1825 by Ambroise Tardieu of Ampere (1775-1836). 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'. He became Professor of Physics and Chemistry at Bourg in 1801 and Professor of Mathematics at the Ecole Polytechnique in Paris in 1809. From a collection of portraits of scientists published by Photographische Gesellschaft, Berlin, 1910.
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