The Zeeman Effect of magnetic fields is usually taught in undergrad-level quantum mechanics classes (physics major track), where a degeneracy of the the solutio

The Zeeman Effect of magnetic fields is usually taught in undergrad-level quantum mechanics classes (physics major track), where a degeneracy of the the solution to Schrodinger's Equation for a hydrogen atom is split into separate levels by the magnetic field. There's a similar effect for electric fields too (the Stark Effect).