Glossary / History of physics
Zeeman effect
The splitting of spectral lines into several when atoms are placed in a magnetic field.
In 1896 the Dutch physicist Pieter Zeeman found that a magnetic field broadens the spectral lines of sodium in a flame, and reported it the following year[1]. Hendrik Lorentz explained it by the motion of charges in the atom, and the two shared the 1902 Nobel Prize in Physics.
In many atoms, however, the lines split differently from the theory's prediction. This anomalous Zeeman effect resisted every attempt within the old quantum theory, and was solved only when electron spin was proposed in 1925.
Related terms
- Fine structureThe splitting of what looks like a single line in an atom's spectrum into several closely spaced lines when examined in detail.
- Old quantum theoryThe theories of roughly 1900 to 1925, from Planck onwards, that explained phenomena by adding quantum conditions on top of classical physics.