An article by L A Geddes and L.E. Geddes, explains how Georg Ohm discovered the Ohm’s law. As the authors tell, Georg Ohm lived at a time when there were no calibrated indicators for electric current: no volt or amp, because these were established much later. The resources available to Ohm were: 1) the discovery of Oersted, who in 1820 showed that a magnetic field surrounded a wire carrying electric current; 2) the electrochemical cell, described by Volta in 1800; and 3) the thermoelectric effect, discovered by Seebeck in 1822. In fact, the Seebeck effect is giving a quite stable source of current.