**Georg Simon Ohm** He was born on March 16, 1789 in Bavaria (Germany), and died on July 6, 1854 in Munich. Physicist and mathematician, Ohm was a math teacher in Cologne and Nuremberg. Between 1825 and 1827, he developed the first mathematical theory of electrical conduction in circuits, based on the study of Fourier heat conduction and fabricating metal wires of different lengths and diameters used in his studies of electrical conduction.

This work of his was not deserved of recognition in his day, and the famous Ohm's law remained unknown until 1841, when he received the Copley Medal from the British Royal. Until that time the jobs he had in Cologne and Nuremberg were not permanent, not allowing him to maintain a reasonable standard of living.

He worked as a secondary mathematics teacher at the Jesuit College in Cologne, but wanted to teach at the university. To this end, he was required, as proof of admission, to undertake unpublished research work. He chose to experiment with electricity and built his own equipment, including wires.

Experimenting with different wire thicknesses and lengths, he discovered extremely simple mathematical relationships involving these dimensions and electrical quantities. Initially, it found that the current intensity was directly proportional to the area of the wire section and inversely proportional to its length. With this, Ohm was able to define a new concept: that of electrical resistance. What does electrical resistance mean? The free electrons that flow along the electrical wire or cable must pass through the atoms that compose it, constantly colliding with them. In this way, the flow of electrons is impeded by the resistance that atoms oppose to their passage.

In 1827, Ohm was able to formulate a statement that involved, besides these quantities, the potential difference: "The intensity of the electric current that flows through a conductor is directly proportional to the potential difference and inversely proportional to the circuit resistance." This statement is still known today as Ohm's Law. These relations had also been pointed out half a century earlier by the English Cavendish, who did not disclose them.

Although these studies were an important collaboration in the theory of electrical circuits and their applications, Ohm's desired university post was denied him. His conclusions received negative criticism, in part because he tried to explain these phenomena based on a theory of heat flow. Ohm even had to resign from his high school job in Cologne, and lived in poverty for the next six years. In 1833, however, he reintegrated into scientific activities by accepting a post at the Nuremberg Polytechnic School.

In 1841, he received a medal from the Royal Society of London, and only in 1849 did Ohm succeed in becoming a professor at the University of Munich, where he remained for only five years, the last of his life.