Georg Ohm
Overview
 
Georg Simon Ohm was a German physicist
Physicist
A physicist is a scientist who studies or practices physics. Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made to the behavior of the material Universe as a whole...

. As a high school teacher, Ohm began his research with the recently-invented electrochemical cell
Electrochemical cell
An electrochemical cell is a device capable of either deriving electrical energy from chemical reactions, or facilitating chemical reactions through the introduction of electrical energy. A common example of an electrochemical cell is a standard 1.5-volt "battery"...

, invented by Italian Count Alessandro Volta
Alessandro Volta
Count Alessandro Giuseppe Antonio Anastasio Gerolamo Umberto Volta was a Lombard physicist known especially for the invention of the battery in 1800.-Early life and works:...

. Using equipment of his own creation, Ohm determined that there is a direct proportionality between the potential difference (voltage
Voltage
Voltage, otherwise known as electrical potential difference or electric tension is the difference in electric potential between two points — or the difference in electric potential energy per unit charge between two points...

) applied across a conductor and the resultant electric current
Electric current
Electric current is a flow of electric charge through a medium.This charge is typically carried by moving electrons in a conductor such as wire...

. This relationship is known as Ohm's law
Ohm's law
Ohm's law states that the current through a conductor between two points is directly proportional to the potential difference across the two points...

.
Georg Simon Ohm was born in Erlangen
Erlangen
Erlangen is a Middle Franconian city in Bavaria, Germany. It is located at the confluence of the river Regnitz and its large tributary, the Untere Schwabach.Erlangen has more than 100,000 inhabitants....

, Bavaria
Bavaria
Bavaria, formally the Free State of Bavaria is a state of Germany, located in the southeast of Germany. With an area of , it is the largest state by area, forming almost 20% of the total land area of Germany...

, son to Johann Wolfgang Ohm, a locksmith and Maria Elizabeth Beck, the daughter of a tailor in Erlangen.
Encyclopedia
Georg Simon Ohm was a German physicist
Physicist
A physicist is a scientist who studies or practices physics. Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made to the behavior of the material Universe as a whole...

. As a high school teacher, Ohm began his research with the recently-invented electrochemical cell
Electrochemical cell
An electrochemical cell is a device capable of either deriving electrical energy from chemical reactions, or facilitating chemical reactions through the introduction of electrical energy. A common example of an electrochemical cell is a standard 1.5-volt "battery"...

, invented by Italian Count Alessandro Volta
Alessandro Volta
Count Alessandro Giuseppe Antonio Anastasio Gerolamo Umberto Volta was a Lombard physicist known especially for the invention of the battery in 1800.-Early life and works:...

. Using equipment of his own creation, Ohm determined that there is a direct proportionality between the potential difference (voltage
Voltage
Voltage, otherwise known as electrical potential difference or electric tension is the difference in electric potential between two points — or the difference in electric potential energy per unit charge between two points...

) applied across a conductor and the resultant electric current
Electric current
Electric current is a flow of electric charge through a medium.This charge is typically carried by moving electrons in a conductor such as wire...

. This relationship is known as Ohm's law
Ohm's law
Ohm's law states that the current through a conductor between two points is directly proportional to the potential difference across the two points...

.

Early years

Georg Simon Ohm was born in Erlangen
Erlangen
Erlangen is a Middle Franconian city in Bavaria, Germany. It is located at the confluence of the river Regnitz and its large tributary, the Untere Schwabach.Erlangen has more than 100,000 inhabitants....

, Bavaria
Bavaria
Bavaria, formally the Free State of Bavaria is a state of Germany, located in the southeast of Germany. With an area of , it is the largest state by area, forming almost 20% of the total land area of Germany...

, 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
Martin Ohm
Martin Ohm was a German mathematician and a younger brother of physicist Georg Ohm. He earned his doctorate in 1811 at Friedrich-Alexander-University, Erlangen-Nuremberg where his advisor was Karl Christian von Langsdorf. Ohm was the first to fully develop the theory of the exponential ab when...

, 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
Mathematics is the study of quantity, space, structure, and change. Mathematicians seek out patterns and formulate new conjectures. Mathematicians resolve the truth or falsity of conjectures by mathematical proofs, which are arguments sufficient to convince other mathematicians of their validity...

, physics
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...

, chemistry
Chemistry
Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....

 and philosophy
Philosophy
Philosophy is the study of general and fundamental problems, such as those connected with existence, knowledge, values, reason, mind, and language. Philosophy is distinguished from other ways of addressing such problems by its critical, generally systematic approach and its reliance on rational...

. 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
Daniel Bernoulli
Daniel Bernoulli was a Dutch-Swiss mathematician and was one of the many prominent mathematicians in the Bernoulli family. He is particularly remembered for his applications of mathematics to mechanics, especially fluid mechanics, and for his pioneering work in probability and statistics...

 family, as noted by Karl Christian von Langsdorf
Karl Christian von Langsdorf
Karl Christian von Langsdorf, also known as Carl Christian von Langsdorff, was a German mathematician, geologist, natural scientist and engineer.-Life:...

, a professor at the University of Erlangen
Friedrich-Alexander-University, Erlangen-Nuremberg
The Universität Erlangen Nürnberg is a university in the cities of Erlangen and Nuremberg in Bavaria, Germany. It is the second largest state university in Bavaria, having five Schools, 308 chairs, and 12,000 employees. There are 28,735 students enrolled at the university, of which about 2/3 are...

.

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
Karl Christian von Langsdorf
Karl Christian von Langsdorf, also known as Carl Christian von Langsdorff, was a German mathematician, geologist, natural scientist and engineer.-Life:...

 left the University of Erlangen in early 1809 to take up a post in the University of Heidelberg
Ruprecht Karl University of Heidelberg
The Ruprecht-Karls-Universität Heidelberg is a public research university located in Heidelberg, Baden-Württemberg, Germany. Founded in 1386, it is the oldest university in Germany and was the third university established in the Holy Roman Empire. Heidelberg has been a coeducational institution...

 and Ohm would have liked to have gone with him to Heidelberg
Heidelberg
-Early history:Between 600,000 and 200,000 years ago, "Heidelberg Man" died at nearby Mauer. His jaw bone was discovered in 1907; with scientific dating, his remains were determined to be the earliest evidence of human life in Europe. In the 5th century BC, a Celtic fortress of refuge and place of...

 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
Leonhard Euler
Leonhard Euler was a pioneering Swiss mathematician and physicist. He made important discoveries in fields as diverse as infinitesimal calculus and graph theory. He also introduced much of the modern mathematical terminology and notation, particularly for mathematical analysis, such as the notion...

, Laplace
Pierre-Simon Laplace
Pierre-Simon, marquis de Laplace was a French mathematician and astronomer whose work was pivotal to the development of mathematical astronomy and statistics. He summarized and extended the work of his predecessors in his five volume Mécanique Céleste...

 and Lacroix
Sylvestre François Lacroix
Sylvestre François Lacroix was a French mathematician.He was born in Paris, and was raised in a poor family who still managed to obtain a good education for their son. He displayed a particular talent for mathematics, calculating the motions of theplanets by the age of 14...

. 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
Doctorate
A doctorate is an academic degree or professional degree that in most countries refers to a class of degrees which qualify the holder to teach in a specific field, A doctorate is an academic degree or professional degree that in most countries refers to a class of degrees which qualify the holder...

 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
Bamberg
Bamberg is a city in Bavaria, Germany. It is located in Upper Franconia on the river Regnitz, close to its confluence with the river Main. Bamberg is one of the few cities in Germany that was not destroyed by World War II bombings because of a nearby Artillery Factory that prevented planes from...

 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
Geometry
Geometry arose as the field of knowledge dealing with spatial relationships. Geometry was one of the two fields of pre-modern mathematics, the other being the study of numbers ....

 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.
After that, he sent the manuscript to King Wilhelm III of Prussia
Frederick William III of Prussia
Frederick William III was king of Prussia from 1797 to 1840. He was in personal union the sovereign prince of the Principality of Neuchâtel .-Early life:...

 upon its completion. The King was satisfied with Georg's work and he offered Ohm a position at a Jesuit Gymnasium
Dreikönigsgymnasium
The Dreikönigsgymnasium is a regular public Gymnasium located in Cologne, Germany. Founded in 1450 it is the oldest school in Cologne and one of the oldest in Germany.-Alumni:...

 of Cologne
Cologne
Cologne is Germany's fourth-largest city , and is the largest city both in the Germany Federal State of North Rhine-Westphalia and within the Rhine-Ruhr Metropolitan Area, one of the major European metropolitan areas with more than ten million inhabitants.Cologne is located on both sides of the...

 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
Nuremberg
Nuremberg[p] is a city in the German state of Bavaria, in the administrative region of Middle Franconia. Situated on the Pegnitz river and the Rhine–Main–Danube Canal, it is located about north of Munich and is Franconia's largest city. The population is 505,664...

 in 1833, and in 1852 became professor of experimental physics in the university of Munich
Munich
Munich The city's motto is "" . Before 2006, it was "Weltstadt mit Herz" . Its native name, , is derived from the Old High German Munichen, meaning "by the monks' place". The city's name derives from the monks of the Benedictine order who founded the city; hence the monk depicted on the city's coat...

, where he later died. He is buried in the Alter Südfriedhof
Alter Südfriedhof
The Alter Südfriedhof 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 Gate between Thalkirchner and Pestalozzistraße.-History:...

 in Munich.

The discovery of Ohm's law

Ohm's law first appearedOhm's law, that electric current is proportional to a potential difference, was first discovered by Henry Cavendish
Henry Cavendish
Henry Cavendish FRS was a British scientist noted for his discovery of hydrogen or what he called "inflammable air". He described the density of inflammable air, which formed water on combustion, in a 1766 paper "On Factitious Airs". Antoine Lavoisier later reproduced Cavendish's experiment and...

, 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.
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
Electromotive force
In physics, electromotive force, emf , or electromotance refers to voltage generated by a battery or by the magnetic force according to Faraday's Law, which states that a time varying magnetic field will induce an electric current.It is important to note that the electromotive "force" is not a...

 acting between the extremities of any part of a circuit is the product of the strength of the current
Electric current
Electric current is a flow of electric charge through a medium.This charge is typically carried by moving electrons in a conductor such as wire...

, and the resistance
Electrical resistance
The electrical resistance of an electrical element is the opposition to the passage of an electric current through that element; the inverse quantity is electrical conductance, the ease at which an electric current passes. Electrical resistance shares some conceptual parallels with the mechanical...

 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. 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
Joseph Fourier
Jean Baptiste Joseph Fourier was a French mathematician and physicist best known for initiating the investigation of Fourier series and their applications to problems of heat transfer and vibrations. The Fourier transform and Fourier's Law are also named in his honour...

 and Navier
Claude-Louis Navier
Claude-Louis Navier born Claude Louis Marie Henri Navier , was a French engineer and physicist who specialized in mechanics.The Navier–Stokes equations are named after him and George Gabriel Stokes....

. A detailed study of the conceptual framework
Conceptual framework
A conceptual framework is used in research to outline possible courses of action or to present a preferred approach to an idea or thought. For example, the philosopher Isaiah Berlin used the "hedgehogs" versus "foxes" approach; a "hedgehog" might approach the world in terms of a single organizing...

 used by Ohm in formulating Ohm's law has been presented by Archibald.

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 writings were numerous. The most important was his pamphlet published in Berlin
Berlin
Berlin is the capital city of Germany and is one of the 16 states of Germany. With a population of 3.45 million people, Berlin is Germany's largest city. It is the second most populous city proper and the seventh most populous urban area in the European Union...

 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
Electric current
Electric current is a flow of electric charge through a medium.This charge is typically carried by moving electrons in a conductor such as wire...

. Ohm's name has been incorporated in the terminology of electrical science
Electrical engineering
Electrical engineering is a field of engineering that generally deals with the study and application of electricity, electronics and electromagnetism. The field first became an identifiable occupation in the late nineteenth century after commercialization of the electric telegraph and electrical...

 in Ohm's Law (which he first published in Die galvanische Kette...), the proportionality
Proportionality (mathematics)
In mathematics, two variable quantities are proportional if one of them is always the product of the other and a constant quantity, called the coefficient of proportionality or proportionality constant. In other words, are proportional if the ratio \tfrac yx is constant. We also say that one...

 of current and voltage
Voltage
Voltage, otherwise known as electrical potential difference or electric tension is the difference in electric potential between two points — or the difference in electric potential energy per unit charge between two points...

 in a resistor
Resistor
A linear resistor is a linear, passive two-terminal electrical component that implements electrical resistance as a circuit element.The current through a resistor is in direct proportion to the voltage across the resistor's terminals. Thus, the ratio of the voltage applied across a resistor's...

, and adopted as the SI
Si
Si, si, or SI may refer to :- Measurement, mathematics and science :* International System of Units , the modern international standard version of the metric system...

 unit of resistance
Electrical resistance
The electrical resistance of an electrical element is the opposition to the passage of an electric current through that element; the inverse quantity is electrical conductance, the ease at which an electric current passes. Electrical resistance shares some conceptual parallels with the mechanical...

, 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
Royal Society
The Royal Society of London for Improving Natural Knowledge, known simply as the Royal Society, is a learned society for science, and is possibly the oldest such society in existence. Founded in November 1660, it was granted a Royal Charter by King Charles II as the "Royal Society of London"...

 with its award of the Copley Medal
Copley Medal
The Copley Medal is an award given by the Royal Society of London for "outstanding achievements in research in any branch of science, and alternates between the physical sciences and the biological sciences"...

 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
Bavarian Academy of Sciences and Humanities
The Bavarian Academy of Sciences and Humanities is an independent public institution, located in Munich. It appoints scholars whose research has contributed considerably to the increase of knowledge within their subject...

.

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)

External links

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