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Encyclopedia > Magnetic field density

Magnetic field density, otherwise known as magnetic flux density, is the measurable component of what is essentially what the layman knows as a magnetic field—akin to a gravitational or electric field. It is a response of a medium to the presence of a magnetic field. The SI unit of magnetic flux density is the tesla. 1 tesla = 1 weber per square metre. For the indie-pop band, see The Magnetic Fields. ... A gravitational field is a model used within physics to explain how gravity exists in the universe. ... In physics, the space surrounding an electric charge or in the presence of a time-varying magnetic field has a property called an electric field. ... Look up si, Si, SI in Wiktionary, the free dictionary. ... SI unit. ... In physics, the weber (symbol: Wb) is the SI unit of magnetic flux. ... A square metre (US spelling: square meter) is by definition the area enclosed by a square with sides each 1 metre long. ...

It can be more easily explained if one works backwards from the equation: $B=frac {F} {I L} ,$

where

B is the magnitude of flux density in teslas
F is the force in newtons experienced by a wire carrying
I amperes of current
L metres in length
Demonstration of the left hand rule

1 newton is a lot of force, and is not easily accomplished. To put it in perspective: the most powerful superconducting electromagnets in the world have flux densities of 'only' 20 T. A magnet levitating above a high-temperature superconductor, cooled with liquid nitrogen. ... An electromagnet is a type of magnet in which the magnetic field is produced by the flow of an electric current. ...

This is true obviously for both electromagnets and natural magnets, but a magnetic field can only act on moving charge—hence the current, I, in the equation.

Indeed, the equation can be adjusted to incorporate moving single charges, ie protons, electrons, and so on via

$F = BQv ,$

where

Q is 1 coulomb of charge
v is the velocity of that charge in metre per second

Fleming's left hand rule can be used to determine the direction of motion/current/polarity from any two of those, as seen in the example. It can also remembered in the following way. From the thumb to second finger, indicating 'Force', 'B-field', and 'I(Current)' respectively. Therefore it is F-B-I in short. The coulomb (symbol: C) is the SI unit of electric charge. ... Metre per second (U.S. spelling: meter per second) is an SI derived unit of both speed (scalar) and velocity (vector), defined by distance in metres divided by time in seconds. ... Sir John Ambrose Fleming (November 29, 1849 - April 18, 1945) was an English electrical engineer and physicist. ...

For professional languages, right hand grip rule is used instead which originated from the definition of cross product in the right hand system of coordinates. Prediction of direction of field (B), given that the current I flows in the direction of the thumb. ... For the cross product in algebraic topology, see KÃ¼nneth theorem. ... See Cartesian coordinate system or Coordinates (elementary mathematics) for a more elementary introduction to this topic. ...

Other units of magnetic flux density are

• 1 gauss = 10-4 teslas = 100 microteslas (µT)
• 1 gamma = 10-9 teslas = 1 nanotesla (nT)

The gauss, abbreviated as G, is the cgs unit of magnetic flux density (B), named after the German mathematician and physicist Carl Friedrich Gauss. ... Gamma (uppercase Î“, lowercase Î³) is the third letter of the Greek alphabet. ...

For the indie-pop band, see The Magnetic Fields. ... For thermodynamic relations, see Maxwell relations. ... ...

## References

• Jiles, David (1994). Introduction to Electronic Properties of Materials (1st ed.). Springer. ISBN 0-412-49580-5.

Results from FactBites:

 Magnetic field density - definition of Magnetic field density in Encyclopedia (274 words) Magnetic field density, otherwise known as magnetic flux density, is essentially what the layman knows as a magnetic field - akin to a gravitational or electric field. The SI unit of magnetic flux density is the tesla. B is the magnitude of flux density in teslas
 Magnetic field - Wikipedia, the free encyclopedia (1866 words) (The quantum-mechanical spin of a particle produces magnetic fields and is acted on by them as though it were a current; this accounts for the fields produced by "permanent" ferromagnets.) A magnetic field is a vector field: it associates with every point in space a (pseudo-)vector that may vary in time. Formally, the magnetic field is not a vector, it is a pseudovector. Magnetic field lines point from north to south of a magnet, and hence the natural magnetic field lines run from south to north along the Earth's surface.
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