Georg Simon Ohm (, ; 16 March 1789 – 6 July 1854) was a German
physicist
A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe.
Physicists generally are interested in the root or ultimate caus ...
and
mathematician
A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems.
Mathematicians are concerned with numbers, data, quantity, structure, space, models, and change.
History
On ...
. As a school teacher, Ohm began his research with the new
electrochemical cell
An electrochemical cell is a device capable of either generating electrical energy from chemical reactions or using electrical energy to cause chemical reactions. The electrochemical cells which generate an electric current are called voltaic o ...
, invented by Italian scientist
Alessandro Volta
Alessandro Giuseppe Antonio Anastasio Volta (, ; 18 February 1745 – 5 March 1827) was an Italian physicist, chemist and lay Catholic who was a pioneer of electricity and power who is credited as the inventor of the electric battery and the ...
. Using equipment of his own creation, Ohm found that there is a direct proportionality between the potential difference (
voltage
Voltage, also known as electric pressure, electric tension, or (electric) potential difference, is the difference in electric potential between two points. In a static electric field, it corresponds to the work needed per unit of charge to m ...
) applied across a conductor and the resultant
electric current
An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is measured as the net rate of flow of electric charge through a surface or into a control volume. The moving pa ...
. This relation is called
Ohm's law
Ohm's law states that the current through a conductor between two points is directly proportional to the voltage across the two points. Introducing the constant of proportionality, the resistance, one arrives at the usual mathematical equat ...
, and the
ohm
Ohm (symbol Ω) is a unit of electrical resistance named after Georg Ohm.
Ohm or OHM may also refer to:
People
* Georg Ohm (1789–1854), German physicist and namesake of the term ''ohm''
* Germán Ohm (born 1936), Mexican boxer
* Jörg Ohm (b ...
, the unit of
electrical resistance
The electrical resistance of an object is a measure of its opposition to the flow of electric current. Its reciprocal quantity is , measuring the ease with which an electric current passes. Electrical resistance shares some conceptual parallels ...
, is named after him.
Biography
Early life
Georg Simon Ohm was born into a
Protestant
Protestantism is a Christian denomination, branch of Christianity that follows the theological tenets of the Reformation, Protestant Reformation, a movement that began seeking to reform the Catholic Church from within in the 16th century agai ...
family in
Erlangen
Erlangen (; East Franconian German, East Franconian: ''Erlang'', Bavarian language, Bavarian: ''Erlanga'') is a Middle Franconian city in Bavaria, Germany. It is the seat of the administrative district Erlangen-Höchstadt (former administrative d ...
,
Brandenburg-Bayreuth
The Principality of Bayreuth (german: Fürstentum Bayreuth) or Margraviate of Brandenburg-Bayreuth (''Markgraftum Brandenburg-Bayreuth'') was an immediate territory of the Holy Roman Empire, ruled by a Franconian branch of the Hohenzollern dyna ...
(then part of the
Holy Roman Empire
The Holy Roman Empire was a Polity, political entity in Western Europe, Western, Central Europe, Central, and Southern Europe that developed during the Early Middle Ages and continued until its Dissolution of the Holy Roman Empire, dissolution i ...
), son to locksmith Johann Wolfgang Ohm, and Maria Elizabeth Beck, daughter of a tailor in Erlangen. 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. Of the seven children of the family only three survived to adulthood: Georg Simon, his younger brother
Martin Martin may refer to:
Places
* Martin City (disambiguation)
* Martin County (disambiguation)
* Martin Township (disambiguation)
Antarctica
* Martin Peninsula, Marie Byrd Land
* Port Martin, Adelie Land
* Point Martin, South Orkney Islands
Austr ...
, 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
Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in modern mathematics ...
,
physics
Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...
,
chemistry
Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds made of atoms, molecules and ions ...
and
philosophy
Philosophy (from , ) is the systematized study of general and fundamental questions, such as those about existence, reason, knowledge, values, mind, and language. Such questions are often posed as problems to be studied or resolved. Some ...
. 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
The Bernoulli family () of Basel was a patrician family, notable for having produced eight mathematically gifted academics who, among them, contributed substantially to the development of mathematics and physics during the early modern period.
...
, as noted by
Karl Christian von Langsdorf
Karl Christian von Langsdorf, also known as Carl Christian von Langsdorff (18 May 1757 in Bad Nauheim, Nauheim – 10 June 1834 in Heidelberg), was a German mathematician, geologist, natural scientist and engineer.
Life
Langsdorf was the son of ...
, a professor at the
University of Erlangen
A university () is an institution of higher (or tertiary) education and research which awards academic degrees in several academic disciplines. Universities typically offer both undergraduate and postgraduate programs. In the United States, th ...
.
Life in university
Georg Ohm's father, concerned that his son was wasting his educational opportunity, sent Ohm to Switzerland. There in September 1806 Ohm accepted a position as a mathematics teacher in a school in Gottstadt bei Nidau.
Karl Christian von Langsdorf
Karl Christian von Langsdorf, also known as Carl Christian von Langsdorff (18 May 1757 in Bad Nauheim, Nauheim – 10 June 1834 in Heidelberg), was a German mathematician, geologist, natural scientist and engineer.
Life
Langsdorf was the son of ...
left the University of Erlangen in early 1809 to take up a post in the
University of Heidelberg
}
Heidelberg University, officially the Ruprecht Karl University of Heidelberg, (german: Ruprecht-Karls-Universität Heidelberg; la, Universitas Ruperto Carola Heidelbergensis) is a public research university in Heidelberg, Baden-Württemberg, ...
. Ohm wanted to restart his mathematical studies with Langsdorf in
Heidelberg
Heidelberg (; Palatine German language, Palatine German: ''Heidlberg'') is a city in the States of Germany, German state of Baden-Württemberg, situated on the river Neckar in south-west Germany. As of the 2016 census, its population was 159,914 ...
. Langsdorf, however, advised Ohm to pursue mathematical studies on his own, and suggested that Ohm read works of
Euler
Leonhard Euler ( , ; 15 April 170718 September 1783) was a Swiss mathematician, physicist, astronomer, geographer, logician and engineer who founded the studies of graph theory and topology and made pioneering and influential discoveries in ma ...
,
Laplace and
Lacroix. Rather reluctantly Ohm took his advice but he left his teaching post in
Gottstatt Monastery in March 1809 to become a private tutor in
Neuchâtel
, neighboring_municipalities= Auvernier, Boudry, Chabrey (VD), Colombier, Cressier, Cudrefin (VD), Delley-Portalban (FR), Enges, Fenin-Vilars-Saules, Hauterive, Saint-Blaise, Savagnier
, twintowns = Aarau (Switzerland), Besançon (France), ...
. 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
Ohm's own studies prepared him for his
doctorate
A doctorate (from Latin ''docere'', "to teach"), doctor's degree (from Latin ''doctor'', "teacher"), or doctoral degree is an academic degree awarded by universities and some other educational institutions, derived from the ancient formalism ''l ...
which he received from the University of Erlangen on October 25, 1811. He immediately joined the faculty there as a lecturer in mathematics but left after three semesters because of unpromising prospects. He could not survive on his salary as a lecturer. The
Bavaria
Bavaria ( ; ), officially the Free State of Bavaria (german: Freistaat Bayern, link=no ), is a state in the south-east of Germany. With an area of , Bavaria is the largest German state by land area, comprising roughly a fifth of the total lan ...
n government offered him a post as a teacher of mathematics and physics at a poor quality school in
Bamberg
Bamberg (, , ; East Franconian: ''Bambärch'') is a town in Upper Franconia, Germany, on the river Regnitz close to its confluence with the river Main. The town dates back to the 9th century, when its name was derived from the nearby ' castle. C ...
which Ohm accepted in January 1813. Unhappy with his job, Georg began writing an elementary textbook on
geometry
Geometry (; ) is, with arithmetic, one of the oldest branches of mathematics. It is concerned with properties of space such as the distance, shape, size, and relative position of figures. A mathematician who works in the field of geometry is c ...
as a way to prove his abilities. That school was closed in February 1816. The Bavarian government then sent Ohm to an overcrowded school in Bamberg to help out with the teaching of mathematics.
![Denkmal Ohm TU München](https://upload.wikimedia.org/wikipedia/commons/1/16/Denkmal_Ohm_TU_M%C3%BCnchen.jpg)
After his assignment in Bamberg, Ohm sent his completed manuscript to
King Wilhelm III of Prussia. The King was satisfied with Ohm's book, and offered Ohm a position at the
Jesuit Gymnasium of
Cologne
Cologne ( ; german: Köln ; ksh, Kölle ) is the largest city of the German western States of Germany, state of North Rhine-Westphalia (NRW) and the List of cities in Germany by population, fourth-most populous city of Germany with 1.1 m ...
on 11 September 1817. This school had a reputation for good science education and Ohm was required to teach physics in addition to mathematics. The physics laboratory was well equipped, allowing Ohm to begin experiments in physics. As the son of a locksmith, Ohm had some practical experience with mechanical devices.
Ohm published (''The Galvanic Circuit Investigated Mathematically'') in 1827. Ohm's college did not appreciate his work and Ohm resigned from his position. He then made an application to, and was employed by, the
Polytechnic School of Nuremberg. Ohm arrived at the Polytechnic School of Nuremberg in 1833, and in 1852 he became a professor of experimental physics at the
University of Munich
The Ludwig Maximilian University of Munich (simply University of Munich or LMU; german: Ludwig-Maximilians-Universität München) is a public research university in Munich, Germany. It is Germany's List of universities in Germany, sixth-oldest u ...
.
[
In 1849, Ohm published (''Molecular Physics''). In the preface of this work he stated he hoped to write a second and third volume "and if God gives me length of days for it, a fourth". However, on finding that an original discovery recorded in it was being anticipated by a Swedish scientist he did not publish it, stating: "The episode has given a fresh and deep sense for my mind to the saying 'Man proposes, and God disposes'. The project that gave the first impetus to my inquiry has been dissipated into mist, and a new one, undesigned by me, has been accomplished in its place."
Ohm died in Munich in 1854, and is buried in the ]Alter Südfriedhof
The Alter Südfriedhof (''Old South Cemetery'') also known as "Alter Südlicher Friedhof" is a cemetery in Munich, Germany. It was founded by Duke Albrecht V as a plague cemetery in 1563 about half a kilometer south of the Sendlinger Ga ...
. A collection of his family letters would be compiled in a German book, which shows that he used to sign some of his letters with the expression ''"Gott befohlen, G S Ohm,"'' meaning "Commended to God".
Discovery of Ohm's law
Ohm's law first appeared in the famous book (''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
In electromagnetism and electronics, electromotive force (also electromotance, abbreviated emf, denoted \mathcal or ) is an energy transfer to an electric circuit per unit of electric charge, measured in volts. Devices called electrical ''transd ...
acting between the extremities of any part of a circuit is the product of the strength of the current
Currents, Current or The Current may refer to:
Science and technology
* Current (fluid), the flow of a liquid or a gas
** Air current, a flow of air
** Ocean current, a current in the ocean
*** Rip current, a kind of water current
** Current (stre ...
, and the resistance of that part of the circuit.
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. Ohm presents his theory as one of contiguous action, a theory which opposed the concept of ]action at a distance
In physics, action at a distance is the concept that an object can be affected without being physically touched (as in mechanical contact) by another object. That is, it is the non-local interaction of objects that are separated in space.
Non-c ...
. Ohm believed that the communication of electricity occurred between "contiguous particles" which is the term he himself used. The paper is concerned with this idea, and in particular with illustrating the differences in this scientific approach of Ohm's and the approaches of Joseph Fourier
Jean-Baptiste Joseph Fourier (; ; 21 March 1768 – 16 May 1830) was a French people, French mathematician and physicist born in Auxerre and best known for initiating the investigation of Fourier series, which eventually developed into Fourier an ...
and Claude-Louis Navier
Claude-Louis Navier (born Claude Louis Marie Henri Navier; ; 10 February 1785 – 21 August 1836) was a French mechanical engineer, affiliated with the French government, and a physicist who specialized in continuum mechanics.
The Navier–Stok ...
.
A study of the conceptual framework
A conceptual framework is an analytical tool with several variations and contexts. It can be applied in different categories of work where an overall picture is needed. It is used to make conceptual distinctions and organize ideas. Strong conceptu ...
used by Ohm in producing Ohm's law has been presented by Thomas Archibald. The work of Ohm marked the early beginning of the subject of circuit theory
Circuit may refer to:
Science and technology
Electrical engineering
* Electrical circuit, a complete electrical network with a closed-loop giving a return path for current
** Analog circuit, uses continuous signal levels
** Balanced circui ...
, although this did not become an important field until the end of the century.
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.
Study and publications
His first paper in 1825 examined the decrease in the electromagnetic force produced by a wire as the length of the wire increased. In 1826, he gave a description of conduction in circuits modelled on Fourier's study of heat conduction. This paper continued Ohm's deduction of results from experimental evidence and, particularly in the second, he was able to propose laws which went a long way to explaining results of others working on galvanic electricity. The most important was his pamphlet published in Berlin
Berlin ( , ) is the capital and largest city of Germany by both area and population. Its 3.7 million inhabitants make it the European Union's most populous city, according to population within city limits. One of Germany's sixteen constitue ...
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
An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is measured as the net rate of flow of electric charge through a surface or into a control volume. The moving pa ...
. 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
Voltage, also known as electric pressure, electric tension, or (electric) potential difference, is the difference in electric potential between two points. In a static electric field, it corresponds to the work needed per unit of charge to m ...
in a resistor
A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow, adjust signal levels, to divide voltages, bias active el ...
, and adopted as the SI unit of resistance, the ohm
Ohm (symbol Ω) is a unit of electrical resistance named after Georg Ohm.
Ohm or OHM may also refer to:
People
* Georg Ohm (1789–1854), German physicist and namesake of the term ''ohm''
* Germán Ohm (born 1936), Mexican boxer
* Jörg Ohm (b ...
(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
The Royal Society, formally The Royal Society of London for Improving Natural Knowledge, is a learned society and the United Kingdom's national academy of sciences. The society fulfils a number of roles: promoting science and its benefits, re ...
with its award of the Copley Medal
The Copley Medal is an award given by the Royal Society, for "outstanding achievements in research in any branch of science". It alternates between the physical sciences or mathematics and the biological sciences. Given every year, the medal is t ...
in 1841. 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. At some extent, Charles Wheatstone
Sir Charles Wheatstone FRS FRSE DCL LLD (6 February 1802 – 19 October 1875), was an English scientist and inventor of many scientific breakthroughs of the Victorian era, including the English concertina, the stereoscope (a device for di ...
drew attention to the definitions which Ohm had introduced in the field of physics.[Merz, John Theodore (1903). ]
"A history of European thought in the nineteenth century"
', pp. 365–366
Works
*
*
**English translation:
*
*
*
[First half], 1852
— via Munich Digitization Center
Munich Digitization Center ( German ''Das Münchener Digitalisierungszentrum'' (MDZ)) is an institution dedicated to digitization, Online publication and the long-term archival preservation of the holdings of the Bavarian State Library
The B ...
*
[Second half], 1853
— via Google Books
*
*
[Volume 1 General Physics], 1854
— via Google Books
*
[Volume 2 Special Physics], 1854
— via Google Books
See also
* Ohm (unit)
Ohm (symbol Ω) is a unit of electrical resistance named after Georg Ohm.
Ohm or OHM may also refer to:
People
* Georg Ohm (1789–1854), German physicist and namesake of the term ''ohm''
* Germán Ohm (born 1936), Mexican boxer
* Jörg Ohm (bor ...
Notes
References
External links
*
*
*
*
{{DEFAULTSORT:Ohm, Georg
1789 births
1854 deaths
People from Erlangen
19th-century German physicists
German Protestants
Recipients of the Copley Medal
People associated with electricity
University of Erlangen-Nuremberg alumni
Burials at the Alter Südfriedhof
Foreign Members of the Royal Society