Georg Simon Ohm 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 – now
known as
Ohm's law.
Using the results of his experiments, Ohm was able to define the
fundamental relationship among
voltage,
current, and
resistance, which represents the true
beginning of
electrical circuit
analysis.
Biography
Early years
Georg
Simon Ohm was born at 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 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 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.
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 on physics. Being the son of a
locksmith, Georg had some practical experience with mechanical
equipment.
He published
Die galvanishe Kette, mathematisch berabeitet
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
Ohm's law first appeared in the famous book
Die galvanische
Kette, mathematisch bearbeitet (The Galvanic Circuit
Investigated Mathematically) (1827) in which he gave his complete
theory of electricity. 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. A detailed study of the
conceptual
framework 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 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.
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)
Footnotes
- 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.
- B. Pourprix, "G.-S. Ohm théoricien de l'action contiguë,"
Archives internationales d'histoire des sciences
45(134) (1995), 30-56
- T Archibald, "Tension and potential from Ohm to Kirchhoff,"
Centaurus 31 (2) (1988), 141-163
- Winners of the Copley Medal of the Royal Society of
London
See also
References
- 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.
- B. Pourprix, "G.-S. Ohm théoricien de l'action contiguë,"
Archives internationales d'histoire des sciences
45(134) (1995), 30-56
- T Archibald, "Tension and potential from Ohm to Kirchhoff,"
Centaurus 31 (2) (1988), 141-163
- Winners of the Copley Medal of the Royal Society of
London
External links