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Tesla (unit)

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tesla
Unit systemSI
Unit ofmagnetic flux density
SymbolT
Named afterNikola Tesla
Conversions
1 Tin...... is equal to...
SI base units1kg⋅s−2⋅A−1
Gaussian units≘104G

Thetesla(symbol:T) is the unit ofmagnetic flux density(also calledmagnetic B-fieldstrength) in theInternational System of Units(SI).

One tesla is equal to oneweberpersquare metre.The unit was announced during theGeneral Conference on Weights and Measuresin 1960 and is named[1]in honour ofSerbian-Americanelectricalandmechanical engineerNikola Tesla,upon the proposal of the Slovenian electrical engineerFrance Avčin.

Definition[edit]

A particle, carrying a charge of onecoulomb(C), and moving perpendicularly through a magnetic field of one tesla, at a speed of one metre per second (m/s), experiences a force with magnitude onenewton(N), according to theLorentz force law.That is,

As anSI derived unit,the tesla can also be expressed in terms of other units. For example, amagnetic fluxof 1weber(Wb) through a surface of one square meter is equal to amagnetic flux densityof 1 tesla.[2]That is,

Expressed only inSI base units,1 tesla is: where A isampere,kg iskilogram,and s issecond.[2]

Additional equivalences result from the derivation of coulombs fromamperes(A),: the relationship between newtons andjoules(J),: and the derivation of the weber fromvolts(V),: The tesla is named afterNikola Tesla.As with everySIunit named for a person, its symbol starts with anupper caseletter (T), but when written in full, it follows the rules for capitalisation of acommon noun;i.e.,teslabecomes capitalised at the beginning of a sentence and in titles but is otherwise in lower case.

Electric vs. magnetic field[edit]

In the production of theLorentz force,the difference between electric fields and magnetic fields is that a force from amagnetic fieldon a charged particle is generally due to the charged particle's movement,[3]while the force imparted by an electric field on a charged particle is not due to the charged particle's movement. This may be appreciated by looking at the units for each. The unit ofelectric fieldin theMKS system of unitsis newtons per coulomb, N/C, while the magnetic field (in teslas) can be written as N/(C⋅m/s). The dividing factor between the two types of field is metres per second (m/s), which is velocity. This relationship immediately highlights the fact that whether a staticelectromagnetic fieldis seen as purely magnetic, or purely electric, or some combination of these, is dependent upon one'sreference frame(that is, one's velocity relative to the field).[4][5]

Inferromagnets,the movement creating the magnetic field is theelectron spin[6](and to a lesser extent electronorbital angular momentum). In a current-carrying wire (electromagnets) the movement is due to electrons moving through the wire (whether the wire is straight or circular).

Conversion to non-SI units[edit]

One tesla is equivalent to:[7][page needed]

  • 10,000 (or 104) G (gauss), used in theCGSsystem. Thus, 1 G = 10−4T = 100 μT (microtesla).
  • 1,000,000,000 (or 109) γ (gamma), used ingeophysics.[8]

For the relation to the units of themagnetising field(ampere per metre orOersted), see the article onpermeability.

Examples[edit]

Main article:Orders of magnitude (magnetic field)

The following examples are listed in the ascending order of the magnetic-field strength.

  • 3.2×10−5T(31.869 μT) – strength ofEarth's magnetic fieldat 0° latitude, 0° longitude
  • 4×10−5T(40 μT) – walking under ahigh-voltage power line[9]
  • 5×10−3T(5 mT) – the strength of a typicalrefrigerator magnet
  • 0.3 T – the strength of solar sunspots
  • 1 T to 2.4 T – coil gap of a typical loudspeaker magnet
  • 1.5 T to 3 T – strength of medicalmagnetic resonance imagingsystems in practice, experimentally up to 17 T[10]
  • 4 T – strength of thesuperconductingmagnet built around theCMSdetector atCERN[11]
  • 5.16 T – the strength of a specially designed room temperatureHalbach array[12]
  • 8 T – the strength ofLHCmagnets
  • 11.75 T – the strength of INUMAC magnets, largestMRI scanner[13]
  • 13 T – strength of the superconductingITERmagnet system[14]
  • 14.5 T – highest magnetic field strength ever recorded for an accelerator steering magnet atFermilab[15]
  • 16 T – magnetic field strength required to levitate afrog[16](bydiamagnetic levitationof the water in its body tissues) according to the 2000Ig Nobel Prizein Physics[17]
  • 17.6 T – strongest field trapped in a superconductor in a lab as of July 2014[18]
  • 20 T - strength of the large scale high temperature superconducting magnet developed by MIT and Commonwealth Fusion Systems to be used in fusion reactors[citation needed]
  • 27 T – maximal field strengths ofsuperconducting electromagnetsat cryogenic temperatures
  • 35.4 T – the current (2009) world record for a superconducting electromagnet in a background magnetic field[19]
  • 45 T – the current (2015) world record for continuous field magnets[19]
  • 97.4 T – strongest magnetic field produced by a "non-destructive" magnet[20]
  • 100 T – approximate magnetic field strength of a typicalwhite dwarfstar
  • 1200 T – the field, lasting for about 100 microseconds, formed using the electromagnetic flux-compression technique[21]
  • 109T –Schwinger limitabove which the electromagnetic field itself is expected to become nonlinear
  • 108– 1011T (100 MT – 100 GT) – magnetic strength range ofmagnetarneutron stars

Notes and references[edit]

  1. ^"Details of SI units".sizes. 2011-07-01.Retrieved2011-10-04.
  2. ^abThe International System of Units (SI), 8th edition,BIPM,eds. (2006),ISBN92-822-2213-6,Table 3. Coherent derived units in the SI with special names and symbolsArchived2007-06-18 at theWayback Machine
  3. ^Gregory, Frederick (2003).History of Science 1700 to Present.The Teaching Company.
  4. ^Parker, Eugene (2007).Conversations on electric and magnetic fields in the cosmos.Princeton University press. p. 65.ISBN978-0691128412.
  5. ^Kurt, Oughstun (2006).Electromagnetic and optical pulse propagation.Springer. p. 81.ISBN9780387345994.
  6. ^Herman, Stephen (2003).Delmar's standard textbook of electricity.Delmar Publishers. p. 97.ISBN978-1401825652.
  7. ^McGraw Hill Encyclopaedia of Physics (2nd Edition), C.B. Parker, 1994,ISBN0-07-051400-3
  8. ^"gamma definition".Oxford Reference.Retrieved2 January2024.
  9. ^"EMF: 7. Extremely low frequency fields like those from power lines and household appliances".ec.europa.eu.Archived fromthe originalon 2021-02-24.Retrieved2022-05-13.
  10. ^"Ultra-High Field".Bruker BioSpin. Archived fromthe originalon 21 July 2012.Retrieved4 October2011.
  11. ^"Superconducting Magnet in CMS".Retrieved9 February2013.
  12. ^"The Strongest Permanent Dipole Magnet"(PDF).Retrieved2 May2020.
  13. ^"ISEULT – INUMAC".Retrieved17 February2014.
  14. ^"ITER – the way to new energy".Retrieved19 April2012.
  15. ^Hesla, Leah (13 July 2020)."Fermilab achieves 14.5-tesla field for accelerator magnet, setting new world record".Retrieved13 July2020.
  16. ^Berry, M. V.; Geim, A. K. (1997)."Of Flying Frogs and Levitrons" by M. V. Berry and A. K. Geim, European Journal of Physics, v. 18, 1997, p. 307–13 "(PDF).European Journal of Physics.18(4): 307–313.doi:10.1088/0143-0807/18/4/012.S2CID1499061.Archived fromthe original(PDF)on 8 October 2020.Retrieved4 October2020.
  17. ^"The 2000 Ig Nobel Prize Winners".August 2006.Retrieved12 May2013.)
  18. ^"Superconductor Traps The Strongest Magnetic Field Yet".2 July 2014.Retrieved2 July2014.
  19. ^ab"Mag Lab World Records".Media Center.National High Magnetic Field Laboratory, USA. 2008.Retrieved24 October2015.
  20. ^"World record pulsed magnetic field".Physics World.31 August 2011.Retrieved26 January2022.)
  21. ^D. Nakamura, A. Ikeda, H. Sawabe, Y. H. Matsuda, and S. Takeyama (2018),Magnetic field milestone

External links[edit]

Look upteslain Wiktionary, the free dictionary.
Retrieved from "https://en.wikipedia.org/w/index.php?title=Tesla_(unit)&oldid=1226163416"