The
Zeeman effect (; ), named after the
Dutch physicist
Pieter Zeeman, is the effect of splitting a
spectral line into several components in the presence of a static
magnetic field. It is analogous to the
Stark effect, the splitting of a spectral line into several components in the presence of an
electric field. Also similar to the Stark effect, transitions between different components have, in general, different intensities, with some being entirely forbidden (in the
dipole approximation), as governed by the
selection rules.