Solving the Schrödinger equation in spherical coordinates for a diatomic gas, one finds that the rotational energy leves are given by: [tex]\epsilon_l=K\cdot l(l+1)[/tex] where [tex]l=0,1,2...[/tex] is the rotational quantum number and K is a constant. It is said that each energy level shows a degeneracy of [tex]g_l=2l+1[/tex]. I understand Degeneracy occurs if for different energy levels one has the same value of energy. Is that right?. Is every quantum number representing an energy level? If that, [tex]\epsilon[/tex] is a single valued function of [tex]l[/tex], so I cannot have the same energy for different quantum numbers. How is the thing of [tex]g_l[/tex] obtained, and how is it physically interpretable for let's say [tex]l=1[/tex]?. Thanks in advance.