# Magnetic flux

**Magnetic flux**, usually denoted by

Greek letter Φ, is a measure of quantity of

magnetism, taking account of the strength and the extent of a

magnetic field. The

flux through an element of

area perpendicular to the direction of magnetic field is given by the product of the magnetic field density and the

area element. More generally, magnetic flux is defined by a

scalar product of the magnetic field density and the area element vector. The

Maxwell's equations in the absence of

magnetic monopoles requires that the magnetic flux through a closed surface is zero. The

SI unit of magnetic flux is the

weber.

*Related concepts*: gauss, henry, tesla, maxwell, oersted, weber, volt, and B-Field.

**See also**: Magnetic flux quantum