In the relativistic treatment of the hydrogen atom (excluding QED), the 251/2 and 2P1/2 levels are found to be degenerate. Which of the following best describes why? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a The degeneracy is a result of the rotational symmetry of the H-atom b d e The Darwin and spin-orbit terms exactly cancel for both levels Each individual contribution (mass-velocity, Darwin and spin-orbit) to the splitting only depend on the total angular momentum quantum number j The mass-velocity and Darwin terms exactly cancel for both levels The degeneracy is due to a subtle symmetry of a 1/r potential when n = 1 and would no longer be the case for other n.

In the relativistic treatment of the hydrogen atom (excluding QED), the 251/2 and 2P1/2 levels are found to be degenerate. Which of the following best describes why? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a The degeneracy is a result of the rotational symmetry of the H-atom b d e The Darwin and spin-orbit terms exactly cancel for both levels Each individual contribution (mass-velocity, Darwin and spin-orbit) to the splitting only depend on the total angular momentum quantum number j The mass-velocity and Darwin terms exactly cancel for both levels The degeneracy is due to a subtle symmetry of a 1/r potential when n = 1 and would no longer be the case for other n.