1. The problem statement, all variables and given/known data Transitions between n=109 to n=108 have been observed in highly excited helium atoms and in this case the Bohr model is a valid approximation. Why is this? 2. Relevant equations N/A 3. The attempt at a solution I'm having some problems with this question and it probably comes down to a lack of understanding. I think it may be because the electron that undergoes this transition is so far from the nucleus/the other e- that we can assume they don't interact with one another (such that Bohr model is valid) but I'm not overly sure/don't understand enough. Any help would be greatly appreciated thank you!