| Electromagnetism |
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| Electricity · Magnetism · Magnetic permeability |
Magnetic flux is a measure of the magnetic field lines passing through a surface, such as a loop of wire. The magnetic flux through a closed surface such as a sphere is always zero, because the magnetic field lines going into the closed surface are balanced by field lines coming out.
It is the alignment of electrons in the atomic shells of ferromagnets and the “spinning” electrons in electromagnets, that provides a material with it’s magnetism.
The SI unit of magnetic flux is the Weber (Wb; in derived units, volt-seconds). The CGS unit is the Maxwell.
Magnetic flux is sometimes used by electrical engineers designing systems with electromagnets or designing dynamos. Physicists designing particle accelerators also calculate magnetic flux.