# Why anomalous Zeeman effect is more common? [closed]

Why anomalous Zeeman effect is more common? Gone through many books, searched on Google, but couldn't find the answer.

• More common that what? Also, Wikipedia tells you that the distinction between normal and anomalous effect is a bit outdated. – ACuriousMind Nov 30 '14 at 11:17

Without the spin, one would expect 3 lines in the pattern only because the transition may change a single type of the spin $S$ only, by $\pm 1$, roughly speaking, from the spin of the photon. Quantum mechanically including the spin, there are transitions between many different states with various values of $L,S$ and other parts of the angular momentum, and they're allowed quantum mechanically as long as the total $J$ angular momentum is conserved.
One gets the "normal" Zeeman effect in the real world only for some simple – perhaps vanishing etc. – arrangements of $L,S$, which is rare, so most of the real-world Zeeman effects are those that were called "anomalous" because they couldn't have been explained without the spin.