Light and magnetism

Maxwell thought that light was electromagnetic radiation, but whatever charge doing the oscillating had yet to be found. Lorentz and his student Zeeman suggested there might be electric charges within the atom, and found them by placing a strong magnetic field near an atom, confirming their spectral lines had changed.
 Hendrik Antoon Lorentz and Pieter Zeeman Netherlands 1896 Light and magnetism

Maxwell thought that light was electromagnetic radiation, but whatever charge doing the oscillating had yet to be found. Lorentz and his student Zeeman suggested there might be electric charges within the atom, and found them by placing a strong magnetic field near an atom, confirming their spectral lines had changed.