Gauss's law for magnetism

Maxwell’s equation stating that the net magnetic flux through any closed surface is zero. It expresses the observed absence of isolated magnetic monopoles.

Magnetic flux: A measure of the magnetic field passing through a surface, calculated from the field’s component normal to that surface. The law states that magnetic flux sums to zero over every closed surface.
Closed surface: A surface enclosing a volume, with no boundary edge through which the volume remains open. The zero-flux statement applies to complete boundaries, not arbitrary open patches.
Magnetic monopole: A hypothetical isolated magnetic charge that would act as a source or sink of magnetic field. Its existence would require modifying the law’s zero-divergence statement.
Solenoidal vector field: A vector field whose divergence is zero throughout its domain. In ordinary electromagnetism, the magnetic field is solenoidal by this law.
Divergence: A measure of the net outward flow of a vector field from an infinitesimal region. The law’s differential form says the divergence of the magnetic field vanishes everywhere.
Surface integral: An integral that accumulates a scalar or vector quantity across a surface. Magnetic flux through a closed surface is evaluated as a surface integral.
Gauss's law for electricity: Maxwell’s equation relating electric flux through a closed surface to the charge enclosed. Electric charge creates field sources, whereas this law permits no observed magnetic counterpart.
Magnetostatics: The study of magnetic fields produced by steady currents and stationary magnetized matter. The law supplies a constraint when solving for static magnetic fields.
Maxwell's equations: Four equations describing how electric and magnetic fields are produced and interact. This law is one of the four equations governing classical electromagnetism.
Magnetic field lines: Curves used to visualize a magnetic field, tangent to the field direction at each point. The law implies these curves have no isolated starting or ending points.

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