Georg Ohm

Georg Simon Ohm was born on March 16, 1789, in Erlangen, a university town in Franconia that would later belong to the Kingdom of Bavaria ^[1]. His father, Johann Wolfgang Ohm, worked as a master locksmith, and his mother, Maria Elizabeth Beck, was the daughter of a tailor. Of the seven children born to the couple, only three survived to adulthood: Georg, his younger brother Martin, and a sister named Elizabeth Barbara ^[2].

The household was modest, but it was anything but intellectually poor. Johann Wolfgang Ohm had received no formal schooling, yet he taught himself mathematics, physics, chemistry, and philosophy to a remarkable standard, and he passed that education directly to his sons. The instruction worked. Martin Ohm went on to become a well-known mathematician in his own right, eventually holding a professorship in Berlin ^[2]. A professor at the University of Erlangen, Karl Christian von Langsdorf, examined the teenage brothers and compared their mathematical talent to that of the Bernoulli family, the famous Swiss dynasty of mathematicians ^[1].

Georg entered the Erlangen Gymnasium at age eleven, though the school offered rote instruction that added little to what his father had already given him. In 1805 he enrolled at the University of Erlangen, where his studies soon drifted toward dancing, ice skating, and billiards. His father, angry at the waste of a rare opportunity, pulled him out of the university after three semesters and sent him to Switzerland, where in 1806 the sixteen-year-old took a post teaching mathematics at a school in Gottstadt bei Nydau ^[2].

Anyone asking who was Georg Ohm before 1827 would have found a provincial schoolmaster with large ambitions and little standing. He returned to Erlangen in 1811, completed a doctorate there in October of that year, and briefly lectured at the university as an unsalaried instructor. The position paid too poorly to live on, so he accepted a teaching job at a mediocre school in Bamberg, work he found dispiriting ^[2].

His fortunes improved in 1817 when he published a textbook on the teaching of geometry and, on its strength, received an offer from the Jesuit Gymnasium in Cologne. The Cologne school was a genuine step up: it had a reputation for science instruction and, crucially, a well-equipped physics laboratory ^[1]. Ohm taught mathematics and physics there and used his free hours to read the French masters, working through Lagrange, Legendre, Laplace, Biot, and Poisson on his own, and later Fourier, whose analytical theory of heat would shape his greatest work ^[2].

Around 1825 Ohm began his own experimental research on the electric circuit, motivated partly by scientific curiosity and partly by a very practical hope: a major publication might win him a university appointment and free him from the schoolroom. Hans Christian Oersted's 1820 discovery that an electric current deflects a magnetic needle had opened a new field, and Ohm set out to bring mathematical order to it ^[1]. His early experiments used voltaic piles as sources, but these gave unsteady currents. On the advice of Johann Poggendorff, he switched to a thermocouple, a junction of two metals that produces a steady voltage from a temperature difference, and with this stable source his measurements became decisive ^[3].

The list of Georg Ohm achievements begins and effectively ends with a single towering result, though that result reorganized an entire science. Working in Cologne between 1825 and 1826, Ohm measured how the current through a wire depended on the wire's length, thickness, and material, and on the electrical push supplied by his thermocouple. He found a simple proportionality: the current flowing in a conductor is directly proportional to the potential difference across it and inversely proportional to its resistance ^[1]. Written today as I equals V divided by R, this relationship is known everywhere as Ohm's law.

He announced his experimental findings in papers of 1826 and then gave the work full theoretical treatment in his 1827 book, Die galvanische Kette, mathematisch bearbeitet, usually translated as The Galvanic Circuit Investigated Mathematically ^[3]. Modeling the flow of electricity on Fourier's treatment of the flow of heat, Ohm introduced clear working definitions of quantities such as electromotive force, current strength, and resistance, and showed how they governed complete circuits rather than isolated wires. The book supplied the conceptual vocabulary that circuit analysis still uses ^[4].

The German scientific establishment received the book coldly. Some critics objected to the mathematical approach itself, preferring a physics grounded in direct qualitative observation, and one reviewer dismissed the work in harsh terms ^[2]. Ohm, who had hoped the book would lift him into a university chair, instead resigned his Cologne post in frustration in 1828 and spent six lean years in Berlin teaching part time at military schools ^[1].

Ohm's later research extended beyond circuits. In 1843 he published work on acoustics stating that the human ear analyzes a complex sound into its component pure tones, a principle now called Ohm's acoustic law. The claim drew criticism from the physicist August Seebeck at the time, but a refined version was later taken up and defended by Hermann von Helmholtz, and it became foundational for the physiology of hearing ^[5].

Vindication came from outside Germany. British and American investigators testing telegraph lines and circuits found that Ohm's simple law worked, and worked everywhere. In 1841 the Royal Society of London awarded Ohm the Copley Medal, then the most prestigious scientific honor in the world, citing his researches into the laws of electric currents ^[3]. The following year the Royal Society elected him a foreign member, placing the former Gymnasium teacher in the company of the era's leading scientists ^[1].

German recognition, slower to arrive, followed the foreign applause. Ohm had left Berlin in 1833 to become professor of physics at the Polytechnic School in Nuremberg, a respectable post though still not the university chair he wanted; he later served as the school's director ^[2]. In 1845 he became a full member of the Bavarian Academy of Sciences in Munich, and in 1849 he moved to Munich to work for the academy and lecture at the university there.

The final prize came very late. In 1852, two years before his death, the University of Munich appointed Ohm to its chair of experimental physics ^[1]. He had pursued exactly that kind of appointment for a quarter of a century, and he held it for only a short time.

Ohm never married and left no children. His closest lifelong bond was with his brother Martin, the Berlin mathematics professor, who had shared the extraordinary home schooling of their father and who remained a correspondent and ally through Georg's years of professional frustration ^[2].

Contemporary accounts describe a man devoted almost entirely to work. Decades of teaching duties in Bamberg, Cologne, Berlin, and Nuremberg left him limited time for research, and much of his experimental apparatus he built or adapted himself, drawing on the mechanical skills learned in his father's locksmith workshop ^[1]. That practical training mattered: precise measurement of feeble currents in the 1820s demanded steady hands and homemade instruments as much as theoretical insight.

His financial situation stayed tight for most of his life. School salaries in the German states of the period were meager, and the years between his resignation from Cologne in 1828 and the Nuremberg appointment in 1833 were especially difficult, supported by piecemeal teaching work ^[2].

The Munich years brought Ohm the security and status that had eluded him for so long. As a member of the Bavarian Academy of Sciences and, from 1852, professor at the University of Munich, he finally taught university students as an acknowledged authority rather than petitioning from the margins ^[1]. He continued to write, producing work on molecular physics that he did not live to complete, and a textbook of geometry treated as an exercise in rigorous deductive training.

His health gave way in the summer of 1854. Georg Simon Ohm died in Munich on July 6, 1854, at the age of sixty-five ^[3]. He was buried in Munich's Alter Südfriedhof, the old southern cemetery that holds the graves of many notable residents of the city ^[6].

Memorials followed in the city where he ended his career. A monument to Ohm stands in Munich, and the Technische Hochschule Nürnberg, the successor of the polytechnic he once directed, is named the Georg Simon Ohm institution in his honor ^[6].

Few scientists have their names spoken as often as Ohm, even if most speakers never think of the man. In 1881 the International Electrical Congress in Paris adopted the ohm as the unit of electrical resistance, and it remains one of the derived units of the modern International System, symbolized by the Greek letter omega ^[4]. Every resistor label, every multimeter reading, every electronics lesson repeats his name.

The deeper legacy is methodological. Ohm's insistence on exact measurement combined with mathematical law, at a time when much German physics distrusted that approach, helped push the discipline toward the quantitative style that dominated the later nineteenth century ^[2]. Circuit theory, telegraphy, power distribution, and eventually all of electronics rest on the relationship he established with a thermocouple, some wires, and a torsion balance in a Cologne school laboratory.

A fair Georg Ohm biography also records the cost of that achievement. He worked for roughly twenty-five years in secondary schools while producing research of the first rank, and his central discovery was slighted at home until foreigners honored it. Among the standard Georg Ohm facts, that long delay between discovery and recognition is perhaps the most instructive: the value of a scientific idea and the speed of its acceptance are two different things ^[1]. Ohm lived long enough to see the gap close, which is more than many of his neglected contemporaries could say.