Thanks for the welcome on behalf of the list John :) I realise atomic
physics has moved on and,yes, I got the hits too, but it's hard to find
anything on this and my world is barren when it comes to (old) references
offline.
Thanks Jack. I think an alternative way for me to ask the question is:
Why didn't Sommerfeld choose orbits in the same shell (same 'n')to have
the same average radius from the focus (be they elliptical or circular).
This would mean electrons in any orbit would have the same average PE and,
if their total energy (KE+PE)is equal, they would have the same average KE
too. What was the guiding principle (or mathematics)?