Electromagnet, c. 1890
Inv V09748

In 1896 Peter Zeeman, while still assistant to Hendrik Antoon Lorentz in Leiden, made an important discovery with this powerful electromagnet. He demonstrated that the spectral lines of which light is made up are split in a powerful magnetic field: the Zeeman effect.

It was not the first time that the interaction between light and magnetism had been shown. What made this discovery particularly important were the theoretical consequences. Lorentz was able to explain the new phenomenon with his newly developed electron theory. In 1902 the two researchers jointly received the Nobel Prize for physics.