Georg Simon Ohm, German physicist, c 1840.
© Science Museum / Science & Society Picture Library
Photogravure after a painting. George Simon Ohm (1789-1854) was Profesor of Physics at Nuremburg and Munich Universities. He is famous for discovering the law governing the relationships between voltage resistance and electric currents. 'Ohm's Law' states that the relationship of current through most materials is directly proportional to the potential difference applied acros the material (V=IR). His findings were published in 1827 in his seminal work on the theory of electricity, 'Die galvanische Kette, mathematische bearbeitet'. The SI unit (International System of scientific units) of electrical resistivity, the Ohm, is named after him. From a collection of portraits of scientists published by Photographische Gesellschaft, Berlin, 1910. Dimensions: 460mm x 340mm.