Gauss's law for magnetism

In physics, Gauss's law for magnetism is one of the four Maxwell's equations that underlie classical electrodynamics. It states that the magnetic field B has divergence equal to zero,[1] in other words, that it is a solenoidal vector field. It is equivalent to the statement that magnetic monopoles do not exist.[2] Rather than "magnetic charges", the basic entity for magnetism is the magnetic dipole. (If monopoles were ever found, the law would have to be modified, as elaborated below.)

Gauss's law for magnetism can be written in two forms, a differential form and an integral form. These forms are equivalent due to the divergence theorem.

The name "Gauss's law for magnetism"[1] is not universally used. The law is also called "Absence of free magnetic poles".[2] It is also referred to as the "transversality requirement"[3] because for plane waves it requires that the polarization be transverse to the direction of propagation.

  1. ^ a b Chow, Tai L. (2006). Electromagnetic Theory: A modern perspective. Jones and Bartlett. p. 134. ISBN 0-7637-3827-1.
  2. ^ a b Jackson, John David (1999). Classical Electrodynamics (3rd ed.). Wiley. p. 237. ISBN 0-471-30932-X.
  3. ^ Joannopoulos, John D.; Johnson, Steve G.; Winn, Joshua N.; Meade, Robert D. (2008). Photonic Crystals: Molding the Flow of Light (2nd ed.). Princeton University Press. p. 9. ISBN 978-0-691-12456-8.