Name this weaker version  of the Paschen-Back effect in which a magnetic field acting on an atom causes the splitting of spectral  lines.
This effect is given a different name if its magnetic field is strong enough to couple the orbital and   spin angular momentums. Its size can be calculated by assuming two electrons are spinning in  opposite directions in the same plane and finding the change in velocity and therefore energy of   the electrons caused by adding a magnetic field. Because this was discovered before the concept of  electron spin was understood, a common version of it is called anomalous. Name this weaker version  of the Paschen-Back effect in which a magnetic field acting on an atom causes the splitting of spectral  lines.
This effect is given a different name if its magnetic field is strong enough to couple the orbital and   spin angular momentums.
{Zeeman} [ZAY-mun] effect