As far as I know: the possible orientations that the total angular momentum can take (given my Mj) are degenerate. if we apply a magnetic field, degeneracy will be lost and different states arise. this is the zeeman effect but when looking up on google for zeeman effect, a webpage used as an example the splitting of the ml values por p orbitals. hence it said that in a magnetic field, the three different orientations of the orbital angular momentum would not be degenerate and hence px py pz would have different energies. What I don't get is why are they talking about orbital angular momentum without including the spin angular momentum and hence talking about L instead of J ??????????