Edwin Hall
Edwin Herbert Hall
American physicist (1855–1938)
Hall was born in Great Falls, Maine, and educated at Johns Hopkins University, Baltimore, where he received his PhD in 1880. After a year in Europe he joined the Harvard faculty and was appointed professor of physics in 1895, a post he held until his retirement in 1921.
While working for his thesis, Hall began to consider a problem first posed by Maxwell concerning the force on a conductor carrying a current in a magnetic field. Does the force act on the conductor or the current? Hall argued that if the current was affected by the magnetic field then there should be “a state of stress…the electricity passing toward one side of the wire.” Hall used a thin gold foil and in 1879 detected for the first time an electric potential acting perpendicularly to both the current and the magnetic field. The effect has since been known as the Hall effect. A simple interpretation is that the charge carriers moving along the conductor experience a transverse force and tend to drift to one side. The sign of the Hall voltage gives information on whether the charge carriers are positive or negative.
Other so-called galvanomagnetic effects were later discovered by Walter Nernst and others. Hall spent much of his later life attempting to measure the various effects as exactly as possible.
More than a century after its discovery Klaus von Klitzing was awarded the 1985 Nobel Prize for physics for his work on the Hall effect.
Edwin Hall
| Edwin Hall | |
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.jpg) Edwin Herbert Hall (1855-1938) |
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| Born | November 7, 1855 Gorham, Maine, USA |
| Died | November 20, 1938 (aged 83) Cambridge, Massachusetts, USA |
| Fields | Physicist |
| Institutions | Harvard University |
| Alma mater | Johns Hopkins University Bowdoin College |
| Doctoral advisor | Henry Augustus Rowland |
| Known for | Hall effect |
Edwin Herbert Hall (November 7, 1855 – November 20, 1938) was an American physicist who discovered the "Hall effect". Hall conducted thermoelectric research at Harvard and also wrote numerous physics textbooks and laboratory manuals.
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Contents
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Biography
Hall was born in Gorham, Maine, U.S.. Hall did his undergraduate work at Bowdoin College, Brunswick, Maine, graduating in 1875. He did his graduate schooling and research, and earned his Ph.D. degree (1880), at the Johns Hopkins University where his seminal experiments were performed.
The Hall effect was discovered by Hall in 1879, while working on his doctoral thesis in Physics.[1] Hall's experiments consisted of exposing thin gold leaf (and, later, using various other materials) on a glass plate and tapping off the gold leaf at points down its length. The effect is a potential difference (Hall voltage) on opposite sides of a thin sheet of conducting or semiconducting material (the Hall element) through which an electric current is flowing. This was created by a magnetic field applied perpendicular to the Hall element. The ratio of the voltage created to the amount of current is known as the Hall resistance, and is a characteristic of the material in the element. In 1880, Hall's experimentation was published as a doctoral thesis in the American Journal of Science and in the Philosophical Magazine.
Hall was appointed as Harvard's professor of physics in 1895. He was notable for lecturing without shoes. Hall retired in 1921 and died in Cambridge, Massachusetts, U.S. in 1938.
The Hall effect is used in magnetic field sensors, present in a large number of devices.
In the presence of large magnetic field strength and low temperature, one can observe the quantum Hall effect, which is the quantization of the Hall resistance. This is now the official standard for electrical resistance.
See also
Relevant lists
- List of eponyms
- List of physicists
References
- ^ Bridgeman, P. W. (1939). Biographical Memoir of Edwin Herbert Hall. National Academy of Sciences. https://docs.google.com/viewer?a=v&q=cache:qWPFjF1DGJcJ:books.nap.edu/html/biomems/ehall.pdf+&hl=en&gl=us&pid=bl&srcid=ADGEESiwi2QsmBBlJQ-CGCqOI-5jo7JVHR8KlVBUlYQg7o3jZTM3Hf2pSa3VeYGFgqCsepNg2dtCFeumBvFAX35h7vFrDq29vFqmPQsXXinsEp4aY1iC4-Tyws_IxDAUX0Gacg8xWCGQ&sig=AHIEtbSYLSS-LvLf1yfIKBflgxKm-7Qwdw.
External links
- Katz, Eugenii, "Hall". Biosensors & Bioelectronics.
- The President and Fellows of Harvard College, "Hall, Edwin Herbert, 1855-1938. Papers: Guide.". Houghton Library, Harvard College Library, Harvard University, Cambridge, MA. 2002.
- "Edwin Hall image". aip.org.
- Hall, Edwin, "On a New Action of the Magnet on Electric Currents". American Journal of Mathematics vol 2 1879.
Works by Hall
He made various contributions to scientific journals on the thermal conductivity of iron and nickel, the theory of thermoelectric action, and on thermoelectric heterogeneity in metals. His publications include:
- A Text-Book of Physics (1891; third edition, 1903), with J. Y. Bergen
- Elementary Lessons in Physics (1894; 1900)
- The Teaching of Chemistry and Physics (1902), with Alexander Smith
- College Laboratory Manual of Physics (1904; revised edition, 1913)
- Elements of Physics (1912)
This article incorporates text from a publication now in the public domain: Gilman, D. C.; Thurston, H. T.; Moore, F., eds. (1905). "article name needed". New International Encyclopedia (1st ed.). New York: Dodd, Mead.
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