Tesla (unit)

Last updated
tesla
Unit system SI
Unit of magnetic flux density
SymbolT
Named after Nikola Tesla
Conversions
1 T in ...... is equal to ...
    SI base units    1 kgs −2A −1
    Gaussian units    104  G

The tesla (symbol: T) is the unit of magnetic flux density (also called magnetic B-field strength) in the International System of Units (SI).

Contents

One tesla is equal to one weber per square metre. The unit was announced during the General Conference on Weights and Measures in 1960 and is named [1] in honour of Serbian-American electrical and mechanical engineer Nikola Tesla, upon the proposal of the Slovenian electrical engineer France Avčin.

Definition

A particle, carrying a charge of one coulomb (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 one newton (N), according to the Lorentz force law. That is,

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

Expressed only in SI base units, 1 tesla is: where A is ampere, kg is kilogram, and s is second. [2]

Additional equivalences result from the derivation of coulombs from amperes (A), : the relationship between newtons and joules (J), : and the derivation of the weber from volts (V), : The tesla is named after Nikola Tesla . As with every SI unit named for a person, its symbol starts with an upper case letter (T), but when written in full, it follows the rules for capitalisation of a common noun ; i.e., tesla becomes capitalised at the beginning of a sentence and in titles but is otherwise in lower case.

Electric vs. magnetic field

In the production of the Lorentz force, the difference between electric fields and magnetic fields is that a force from a magnetic field on 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 of electric field in the MKS system of units is 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 static electromagnetic field is seen as purely magnetic, or purely electric, or some combination of these, is dependent upon one's reference frame (that is, one's velocity relative to the field). [4] [5]

In ferromagnets, the movement creating the magnetic field is the electron spin [6] (and to a lesser extent electron orbital 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

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

For the relation to the units of the magnetising field (ampere per metre or Oersted), see the article on permeability.

Examples

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

Notes and references

  1. "Details of SI units". sizes.com. 2011-07-01. Retrieved 2011-10-04.
  2. 1 2 The International System of Units (SI), 8th edition, BIPM, eds. (2006), ISBN   92-822-2213-6, Table 3. Coherent derived units in the SI with special names and symbols Archived 2007-06-18 at the Wayback 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. ISBN   978-0691128412.
  5. Kurt, Oughstun (2006). Electromagnetic and optical pulse propagation. Springer. p. 81. ISBN   9780387345994.
  6. Herman, Stephen (2003). Delmar's standard textbook of electricity. Delmar Publishers. p. 97. ISBN   978-1401825652.
  7. McGraw Hill Encyclopaedia of Physics (2nd Edition), C.B. Parker, 1994, ISBN   0-07-051400-3
  8. "gamma definition". Oxford Reference. Retrieved 2 January 2024.
  9. "EMF: 7. Extremely low frequency fields like those from power lines and household appliances". ec.europa.eu. Archived from the original on 2021-02-24. Retrieved 2022-05-13.
  10. "Ultra-High Field". Bruker BioSpin. Archived from the original on 21 July 2012. Retrieved 4 October 2011.
  11. "Superconducting Magnet in CMS" . Retrieved 9 February 2013.
  12. "The Strongest Permanent Dipole Magnet" (PDF). Retrieved 2 May 2020.
  13. "ISEULT – INUMAC" . Retrieved 17 February 2014.
  14. "ITER – the way to new energy" . Retrieved 19 April 2012.
  15. Hesla, Leah (13 July 2020). "Fermilab achieves 14.5-tesla field for accelerator magnet, setting new world record" . Retrieved 13 July 2020.
  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. S2CID   1499061. Archived from the original (PDF) on 8 October 2020. Retrieved 4 October 2020.
  17. "The 2000 Ig Nobel Prize Winners". August 2006. Retrieved 12 May 2013.)
  18. "Superconductor Traps The Strongest Magnetic Field Yet". 2 July 2014. Retrieved 2 July 2014.
  19. 1 2 "Mag Lab World Records". Media Center. National High Magnetic Field Laboratory, USA. 2008. Retrieved 24 October 2015.
  20. "World record pulsed magnetic field". Physics World. 31 August 2011. Retrieved 26 January 2022.)
  21. D. Nakamura, A. Ikeda, H. Sawabe, Y. H. Matsuda, and S. Takeyama (2018), Magnetic field milestone

Related Research Articles

The centimetre–gram–second system of units is a variant of the metric system based on the centimetre as the unit of length, the gram as the unit of mass, and the second as the unit of time. All CGS mechanical units are unambiguously derived from these three base units, but there are several different ways in which the CGS system was extended to cover electromagnetism.

The gauss is a unit of measurement of magnetic induction, also known as magnetic flux density. The unit is part of the Gaussian system of units, which inherited it from the older centimetre–gram–second electromagnetic units (CGS-EMU) system. It was named after the German mathematician and physicist Carl Friedrich Gauss in 1936. One gauss is defined as one maxwell per square centimetre.

<span class="mw-page-title-main">Lorentz force</span> Force acting on charged particles in electric and magnetic fields

In physics, specifically in electromagnetism, the Lorentz force law is the combination of electric and magnetic force on a point charge due to electromagnetic fields. The Lorentz force, on the other hand, is a physical effect that occurs in the vicinity of electrically neutral, current-carrying conductors causing moving electrical charges to experience a magnetic force.

<span class="mw-page-title-main">Magnetism</span> Class of physical phenomena

Magnetism is the class of physical attributes that occur through a magnetic field, which allows objects to attract or repel each other. Because both electric currents and magnetic moments of elementary particles give rise to a magnetic field, magnetism is one of two aspects of electromagnetism.

<span class="mw-page-title-main">Maxwell's equations</span> Equations describing classical electromagnetism

Maxwell's equations, or Maxwell–Heaviside equations, are a set of coupled partial differential equations that, together with the Lorentz force law, form the foundation of classical electromagnetism, classical optics, electric and magnetic circuits. The equations provide a mathematical model for electric, optical, and radio technologies, such as power generation, electric motors, wireless communication, lenses, radar, etc. They describe how electric and magnetic fields are generated by charges, currents, and changes of the fields. The equations are named after the physicist and mathematician James Clerk Maxwell, who, in 1861 and 1862, published an early form of the equations that included the Lorentz force law. Maxwell first used the equations to propose that light is an electromagnetic phenomenon. The modern form of the equations in their most common formulation is credited to Oliver Heaviside.

<span class="mw-page-title-main">Magnetic field</span> Distribution of magnetic force

A magnetic field is a physical field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to the magnetic field. A permanent magnet's magnetic field pulls on ferromagnetic materials such as iron, and attracts or repels other magnets. In addition, a nonuniform magnetic field exerts minuscule forces on "nonmagnetic" materials by three other magnetic effects: paramagnetism, diamagnetism, and antiferromagnetism, although these forces are usually so small they can only be detected by laboratory equipment. Magnetic fields surround magnetized materials, electric currents, and electric fields varying in time. Since both strength and direction of a magnetic field may vary with location, it is described mathematically by a function assigning a vector to each point of space, called a vector field.

Flux describes any effect that appears to pass or travel through a surface or substance. Flux is a concept in applied mathematics and vector calculus which has many applications to physics. For transport phenomena, flux is a vector quantity, describing the magnitude and direction of the flow of a substance or property. In vector calculus flux is a scalar quantity, defined as the surface integral of the perpendicular component of a vector field over a surface.

<span class="mw-page-title-main">Magnet</span> Object that has a magnetic field

A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, steel, nickel, cobalt, etc. and attracts or repels other magnets.

<span class="mw-page-title-main">Henry (unit)</span> SI unit of inductance

The henry is the unit of electrical inductance in the International System of Units (SI). If a current of 1 ampere flowing through a coil produces flux linkage of 1 weber turn, that coil has a self-inductance of 1 henry.‌ The unit is named after Joseph Henry (1797–1878), the American scientist who discovered electromagnetic induction independently of and at about the same time as Michael Faraday (1791–1867) in England.

<span class="mw-page-title-main">Electromagnet</span> Magnet created with an electric current

An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. Electromagnets usually consist of wire wound into a coil. A current through the wire creates a magnetic field which is concentrated in the hole in the center of the coil. The magnetic field disappears when the current is turned off. The wire turns are often wound around a magnetic core made from a ferromagnetic or ferrimagnetic material such as iron; the magnetic core concentrates the magnetic flux and makes a more powerful magnet.

<span class="mw-page-title-main">Ampère's circuital law</span> Concept in classical electromagnetism

In classical electromagnetism, Ampère's circuital law relates the circulation of a magnetic field around a closed loop to the electric current passing through the loop.

The magnetic flux, represented by the symbol Φ, threading some contour or loop is defined as the magnetic field B multiplied by the loop area S, i.e. Φ = BS. Both B and S can be arbitrary, meaning that the flux Φ can be as well but increments of flux can be quantized. The wave function can be multivalued as it happens in the Aharonov–Bohm effect or quantized as in superconductors. The unit of quantization is therefore called magnetic flux quantum.

<span class="mw-page-title-main">Magnetic moment</span> Magnetic strength and orientation of an object that produces a magnetic field

In electromagnetism, the magnetic moment or magnetic dipole moment is the combination of strength and orientation of a magnet or other object or system that exerts a magnetic field. The magnetic dipole moment of an object determines the magnitude of torque the object experiences in a given magnetic field. When the same magnetic field is applied, objects with larger magnetic moments experience larger torques. The strength of this torque depends not only on the magnitude of the magnetic moment but also on its orientation relative to the direction of the magnetic field. Its direction points from the south pole to north pole of the magnet.

In physics, the weber is the unit of magnetic flux in the International System of Units (SI). The unit is derived from the relationship 1 Wb = 1 V⋅s (volt-second). A magnetic flux density of 1 Wb/m2 is one tesla.

<span class="mw-page-title-main">Faraday's law of induction</span> Basic law of electromagnetism

Faraday's law of induction is a law of electromagnetism predicting how a magnetic field will interact with an electric circuit to produce an electromotive force (emf). This phenomenon, known as electromagnetic induction, is the fundamental operating principle of transformers, inductors, and many types of electric motors, generators and solenoids.

<span class="mw-page-title-main">Gaussian units</span> Variant of the centimetre–gram–second unit system

Gaussian units constitute a metric system of physical units. This system is the most common of the several electromagnetic unit systems based on cgs (centimetre–gram–second) units. It is also called the Gaussian unit system, Gaussian-cgs units, or often just cgs units. The term "cgs units" is ambiguous and therefore to be avoided if possible: there are several variants of cgs with conflicting definitions of electromagnetic quantities and units.

<span class="mw-page-title-main">Magnetic circuit</span> Closed loop path containing a magnetic flux

A magnetic circuit is made up of one or more closed loop paths containing a magnetic flux. The flux is usually generated by permanent magnets or electromagnets and confined to the path by magnetic cores consisting of ferromagnetic materials like iron, although there may be air gaps or other materials in the path. Magnetic circuits are employed to efficiently channel magnetic fields in many devices such as electric motors, generators, transformers, relays, lifting electromagnets, SQUIDs, galvanometers, and magnetic recording heads.

<span class="mw-page-title-main">Magnetization</span> Physical quantity, density of magnetic moment per volume

In classical electromagnetism, magnetization is the vector field that expresses the density of permanent or induced magnetic dipole moments in a magnetic material. Accordingly, physicists and engineers usually define magnetization as the quantity of magnetic moment per unit volume. It is represented by a pseudovector M. Magnetization can be compared to electric polarization, which is the measure of the corresponding response of a material to an electric field in electrostatics.

<span class="mw-page-title-main">Current density</span> Amount of charge flowing through a unit cross-sectional area per unit time

In electromagnetism, current density is the amount of charge per unit time that flows through a unit area of a chosen cross section. The current density vector is defined as a vector whose magnitude is the electric current per cross-sectional area at a given point in space, its direction being that of the motion of the positive charges at this point. In SI base units, the electric current density is measured in amperes per square metre.

Magnets exert forces and torques on each other through the interaction of their magnetic fields. The forces of attraction and repulsion are a result of these interactions. The magnetic field of each magnet is due to microscopic currents of electrically charged electrons orbiting nuclei and the intrinsic magnetism of fundamental particles that make up the material. Both of these are modeled quite well as tiny loops of current called magnetic dipoles that produce their own magnetic field and are affected by external magnetic fields. The most elementary force between magnets is the magnetic dipole–dipole interaction. If all magnetic dipoles for each magnet are known then the net force on both magnets can be determined by summing all the interactions between the dipoles of the first magnet and the dipoles of the second magnet.