Tesla (unit)
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The tesla (symbol T) is the SI derived unit of magnetic flux density (or magnetic induction). It is used to define the intensity (density) of a magnetic field. The tesla, equal to one weber per square metre, was defined in 1960[1].
It is named in honor of world renowned inventor, scientist and electrical engineer Nikola Tesla. Tesla's legacy can be seen across modern civilization wherever electricity is used because of his invention of alternating current.
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[edit] Definition
1 T = 1 Wb·m−2 = 1 kg·s−2·A−1= 1N·A−1·m−1 = 1 kg·s−1·C−1
It can be thought of "newton-seconds per coulomb-metre" or as "newton per ampere-metre".
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This SI unit is named after Nikola Tesla. As for all SI units whose names are derived from the proper name of a person, the first letter of its symbol is uppercase (T). But when an SI unit is spelled out, it should always be written in lowercase (tesla), unless it begins a sentence or is the name "degree Celsius".
— Based on The International System of Units, section 5.2.
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[edit] SI multiples
| Multiple | Name | Symbol | Multiple | Name | Symbol | |
|---|---|---|---|---|---|---|
| 100 | tesla | T | ||||
| 101 | decatesla | daT | 10–1 | decitesla | dT | |
| 102 | hectotesla | hT | 10–2 | centitesla | cT | |
| 103 | kilotesla | kT | 10–3 | millitesla | mT | |
| 106 | megatesla | MT | 10–6 | microtesla | µT | |
| 109 | gigatesla | GT | 10–9 | nanotesla | nT | |
| 1012 | teratesla | TT | 10–12 | picotesla | pT | |
| 1015 | petatesla | PT | 10–15 | femtotesla | fT | |
| 1018 | exatesla | ET | 10–18 | attotesla | aT | |
| 1021 | zettatesla | ZT | 10–21 | zeptotesla | zT | |
| 1024 | yottatesla | YT | 10–24 | yoctotesla | yT |
[edit] Explanation
The tesla is the value of the total magnetic flux (a magnet's "power") divided by area. Hence, reducing the affected area will generally increase the magnetic flux density.
This will continue to occur until the material becomes magnetically saturated and/or the magnetic field "leakage" increases so fast that no additional tesla gains are possible.[citation needed]
[edit] Conversions
1 tesla is equivalent to:
- 10,000 gauss (G), used in CGS system
- 109 gammas (γ), used in geophysics
[edit] Examples
- In September 2006, NASA found "potholes" in the magnetic field in the heliosheath around our solar system that are 0.01 nanotesla as reported by Voyager 1[2]
- In outer space the magnetic flux density is between 0.1 and 10 nanoteslas (10−10 T and 10−8 T),
- in the Earth's magnetic field at latitude of 50° is 58 µT (5.8×10−5 T) and on the equator at a latitude of 0° is 31 µT (3.1×10−5 T),
- in a sunspot about 0.15 T,
- a large 30 pound loudspeaker magnet will have a coil gap of 1 T.
- A modern neodymium-iron-boron (NIB) rare earth magnet has a strength of about 1.25 T. A coin-sized neodymium magnet can lift more than 9 kg, and can pinch skin and erase credit cards.
- medical magnetic resonance imaging systems utilize field densities from 1.5 to 2 T in practice, experimentally up to 4 T,[3]
- strongest continuous magnetic field yet produced in a laboratory (Florida State University's National High Magnetic Field Laboratory in Tallahassee, USA), 45 T [4].
- strongest (pulsed) magnetic field yet obtained non-destructively in a laboratory (LANL [5][6]), 100 T,
- strongest (pulsed) magnetic field ever obtained (with explosives) in a laboratory (VNIIEF in Sarov, Russia, 1998), 2800 T [7]
- on a neutron star 1 to 100 megateslas (106 T to 108 T),
- on a magnetar, 0.1 to 100 gigateslas (108 to 1011 T),
- maximum theoretical field strength for a neutron star, and therefore the upper bound thus far for any known phenomenon, 1013 T (10 terateslas).
[edit] References
- ^ sizes.com - details of SI units
- ^ Surprises from the Edge of the Solar System. NASA (2006-09-21).
- ^ Smith, Hans-Jørgen. Magnetic resonance imaging. Medcyclopaedia Textbook of Radiology. GE Healthcare. Retrieved on March 26, 2007.
- ^ World's Most Powerful Magnet Tested Ushers in New Era for Steady High Field Research. National High Magnetic Field Laboratory.
- ^ Laboratory sets high magnetic field records. LANL (2006-08-31).
- ^ One-of-a-kind magnet open for science. PhysOrg.com (2006-10-25).
- ^ With record magnetic fields to the 21st Century. IEEE Xplore.
