This equations computes magnitude of the magnetic flux density (expressed in SI units of Tesla) from magnetic flux and area through which the flux passes.
Magnetic fields are produced by moving electric charges and the intrinsic magnetic moments of elementary particles associated with a fundamental quantum property, their spin.[1][2] In special relativity, electric and magnetic fields are two interrelated aspects of a single object, called the electromagnetic tensor; the split of this tensor into electric and magnetic fields depends on the relative velocity of the observer and charge. In quantum physics, the electromagnetic field is quantized and electromagnetic interactions result from the exchange of photons.
[1] Magnetic field
Source: Wikipedia
URL: http://en.wikipedia.org/wiki/Magnetic_field#The_B-field
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