Georg Ohm

Georg Simon Ohm
Born	17 March 1789(1789-03-17) Erlangen, Germany
Died	6 July 1854(1854-07-06) (aged 65) Munich, Germany
Residence	Germany
Nationality	German
Fields	Physics
Institutions	University of Munich
Alma mater	University of Erlangen
Doctoral advisor	Karl Christian von Langsdorf
Known for	Ohm's law Ohm's phase law Ohm's acoustic law
Notable awards	Copley Medal (1841)

Georg Simon Ohm (17 March 1789 – 6 July 1854) was a German physicist. As a high school teacher, Ohm began his research with the recently-invented electrochemical cell, invented by Italian Count Alessandro Volta. Using equipment of his own creation, Ohm determined that there is a direct proportionality between the potential difference (voltage) applied across a conductor and the resultant electric current. This relationship is known as Ohm's law.

Biography

Early years

Georg Simon Ohm was born in Erlangen, Bavaria, son to Johann Wolfgang Ohm, a locksmith and Maria Elizabeth Beck, the daughter of a tailor in Erlangen. They were a Protestant family. Although his parents had not been formally educated, Ohm's father was a respected man who had educated himself to a high level and was able to give his sons an excellent education through his own teachings. Some of Ohm's brothers and sisters died in their childhood, only three survived. The survivors, including Georg Simon, were his younger brother Martin, who later became a well-known mathematician, and his sister Elizabeth Barbara. His mother died when he was ten.

From early childhood, Georg and Martin were taught by their father who brought them to a high standard in mathematics, physics, chemistry and philosophy. Georg Simon attended Erlangen Gymnasium from age eleven to fifteen where he received little in the area of scientific training, which sharply contrasted with the inspired instruction that both Georg and Martin received from their father. This characteristic made the Ohms bear a resemblance to the Bernoulli family, as noted by Karl Christian von Langsdorf, a professor at the University of Erlangen.

Life in university

His father, concerned that his son was wasting the educational opportunity, sent Ohm to Switzerland where, in September 1806, he took up a post as a mathematics teacher in a school in Gottstadt bei Nydau.

Karl Christian von Langsdorf left the University of Erlangen in early 1809 to take up a post in the University of Heidelberg and Ohm would have liked to have gone with him to Heidelberg to restart his mathematical studies. Langsdorf, however, advised Ohm to continue with his studies of mathematics on his own, advising Ohm to read the works of Euler, Laplace and Lacroix. Rather reluctantly Ohm took his advice but he left his teaching post in Gottstadt bei Nydau in March 1809 to become a private tutor in Neuchâtel. For two years he carried out his duties as a tutor while he followed Langsdorf's advice and continued his private study of mathematics. Then in April 1811 he returned to the University of Erlangen.

Teaching career

His studies had stood him in good position for his receiving a doctorate from Erlangen on 25 October 1811 and he immediately joined the staff as a mathematics lecturer. After three semesters Ohm gave up his university post because of unpromising prospects while he couldn't make both ends meet with the lecturing post. The Bavarian government offered him a post as a teacher of mathematics and physics at a poor quality school in Bamberg and he took up the post there in January 1813. Feeling unhappy with his job, Georg devoted himself to writing an elementary book on Geometry as a way to prove his true ability. The school was then closed down in February 1816. The Bavarian government sent him to an overcrowded school in Bamberg to help out with the mathematics teaching.

Memorial for Ohm at the Technical University of Munich, Campus Theresienstrasse

After that, he sent the manuscript to King Wilhelm III of Prussia upon its completion. The King was satisfied with Georg's work and he offered Ohm a position at a Jesuit Gymnasium of Cologne on 11 September 1817. Thanks to the school's reputation for science education, Ohm found himself required to teach physics as well as mathematics. Luckily, the physics lab was well-equipped, so Ohm devoted himself to experimenting in physics. Being the son of a locksmith, Georg had some practical experience with mechanical equipment.

He published Die galvanishe Kette, mathematisch bearbeitet in 1827, which in English is The Galvanic Circuit Investigated Mathematically. Cologne's Jesuit College did not laud his work and Ohm resigned his professorial position there and instead applied to and was employed by the Polytechnic school of Nuremberg (Nürnberg).

He came to the polytechnic school of Nuremberg in 1833, and in 1852 became professor of experimental physics in the university of Munich, where he later died. He is buried in the Alter Südfriedhof in Munich.

The discovery of Ohm's law

Further information: Ohm's Law

Ohm's law first appeared^{[note 1]} in the famous book Die galvanische Kette, mathematisch bearbeitet (tr., The Galvanic Circuit Investigated Mathematically) (1827) in which he gave his complete theory of electricity. In this work, he stated his law for electromotive force acting between the extremities of any part of a circuit is the product of the strength of the current, and the resistance of that part of the circuit.^[1][2]

The book begins with the mathematical background necessary for an understanding of the rest of the work. While his work greatly influenced the theory and applications of current electricity, it was coldly received at that time. It is interesting that Ohm presents his theory as one of contiguous action, a theory which opposed the concept of action at a distance. Ohm believed that the communication of electricity occurred between "contiguous particles" which is the term Ohm himself used. The paper is concerned with this idea, and in particular with illustrating the differences in scientific approach between Ohm and that of Fourier and Navier.^[3] A detailed study of the conceptual framework used by Ohm in formulating Ohm's law has been presented by Archibald.^[4]

Ohm's acoustic law

Further information: Ohm's acoustic law

Ohm's acoustic law, sometimes called the acoustic phase law or simply Ohm's law, states that a musical sound is perceived by the ear as a set of a number of constituent pure harmonic tones. It is well known to be not quite true.^[5]

Study and publications

His writings were numerous. The most important was his pamphlet published in Berlin in 1827, with the title Die galvanische Kette mathematisch bearbeitet. This work, the germ of which had appeared during the two preceding years in the journals of Schweigger and Poggendorff, has exerted an important influence on the development of the theory and applications of electric current. Ohm's name has been incorporated in the terminology of electrical science in Ohm's Law (which he first published in Die galvanische Kette...), the proportionality of current and voltage in a resistor, and adopted as the SI unit of resistance, the ohm (symbol Ω).

Although Ohm's work strongly influenced theory, at first it was received with little enthusiasm. However, his work was eventually recognized by the Royal Society with its award of the Copley Medal in 1841.^[6] He became a foreign member of the Royal Society in 1842, and in 1845 he became a full member of the Bavarian Academy of Sciences and Humanities.

Works

• Grundlinien zu einer zweckmäßigen Behandlung der Geometrie als höheren Bildungsmittels an vorbereitenden Lehranstalten / entworfen (Guidelines for an appropriate treatment of geometry in higher education at preparatory institutes / notes)

Erlangen : Palm und Enke, 1817. - XXXII, 224 S., II Faltbl. : graph. Darst. (PDF, 11.2 MB)

• Die galvanische Kette : mathematisch bearbeitet (The Galvanic Circuit Investigated Mathematically)

Berlin : Riemann, 1827. - 245 S. : graph. Darst. (PDF, 4.7 MB)

• Elemente der analytischen Geometrie im Raume am schiefwinkligen Coordinatensysteme (Elements of analytic geometry concerning the skew coordinate system)

Nürnberg : Schrag, 1849. - XII, 590 S. - (Ohm, Georg S.: Beiträge zur Molecular-Physik ; 1) (PDF, 81 MB)

• Grundzüge der Physik als Compendium zu seinen Vorlesungen (Fundamentals of physics: Compendium of lectures)

Nürnberg : Schrag, 1854. - X, 563 S. : Ill., graph. Darst. Erschienen: Abth. 1 (1853) - 2 (1854) (PDF, 38 MB)

• Bibliography and PDF files of all articles and books by Georg Simon Ohm

See also

• Martin Ohm
• Ohm (unit)

Notes

1. ^ Ohm's law, that electric current is proportional to a potential difference, was first discovered by Henry Cavendish, but Cavendish did not publish his electrical discoveries in his lifetime and they did not become known until 1879, long after Ohm had independently made the discovery and published himself. Thus the law came to bear the name of Ohm.

References

1. ^ Die galvanische kette: mathematisch By Georg Simon Ohm Pg. 181
2. ^ The galvanic circuit investigated mathematically By Georg Simon Ohm Pg. 202
3. ^ B. Pourprix, "G.-S. Ohm théoricien de l'action contiguë," Archives internationales d'histoire des sciences 45(134) (1995), 30-56
4. ^ T Archibald, "Tension and potential from Ohm to Kirchhoff," Centaurus 31 (2) (1988), 141-163
5. ^ Robert Sekuler (1974). "Spatial Vision". In Mark R. Rosenzweig. Annual Review of Psychology, Vol. 25. Annual Reviews Inc. p. 215. ISBN 9780824302252. http://books.google.com/?id=xjKMgA94MdoC&pg=PA215&dq=%22ohm%27s+acoustic+law%22+%22quarter+truth%22#v=onepage&q=%22ohm%27s%20acoustic%20law%22%20%22quarter%20truth%22&f=false. 
6. ^ Winners of the Copley Medal of the Royal Society of London

External links

• O'Connor, John J.; Robertson, Edmund F., "Georg Ohm", MacTutor History of Mathematics archive, University of St Andrews, http://www-history.mcs.st-andrews.ac.uk/Biographies/Ohm.html .
•  Chisholm, Hugh, ed (1911). "Ohm, Georg Simon". Encyclopædia Britannica (11th ed.). Cambridge University Press. 
•  This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed (1911). Encyclopædia Britannica (11th ed.). Cambridge University Press. 

Persondata
Name	Ohm, Georg
Alternative names
Short description	Physics
Date of birth	16 March 1789
Place of birth	Erlangen, Bavaria, Germany
Date of death	6 July 1854
Place of death	Munich, Germany