With equipment, demonstration and accurate calculations can be performed of how the atom's spectral lines are divided by the influence of a magnetic field (the Zeeman effect).

• The simplest variant is the division of a spectral line into three components (the 'normal Zeeman effect'). In this experiment a Cd spectral lamp with 1 = 634.8 nm is used. The CD lamp is subjected to varying magnetic flux density and the division of the CD line is examined with a Fabry-Perot interferrometer. This wavelength corresponds to a D-P transition (singular transition).

In a magnetic field, the affected energy levels will be divided into 2L + 1 levels. If the selection rules are taken into account, 9 transitions occur, of which 3 always have the same energy. Thus 3 lines arise. If the field is studied diagonally, two lines can be observed which are polarized at right angles to the field and a line which is polarized parallel to the field. If, on the other hand, you make an observation in the direction of the field, you can see 2 circular polarized lines.

The Zeeman laboratory provides accurate values ​​for the energy change DELTA E and the magnetic flux density B. The proportionality factor between DELTA E and B is called Bohr's magneton, my B. This can be calculated with great precision.