In
physics, specifically
electromagnetism, the
magnetic flux (often denoted or ) through a surface is the surface integral of the normal component of the
magnetic field B passing through that surface. The
SI unit of magnetic flux is the
weber (Wb) (in derived units: volt-seconds), and the
CGS unit is the
maxwell. Magnetic flux is usually measured with a fluxmeter, which contains measuring coils and
electronics, that evaluates the change of
voltage in the measuring coils to calculate the magnetic flux.