Obvious first to third shell. E is proportional to [1/n1^2 -1/n2^2] [1/n1^2 -1/n2^2] is more when electron moves from the first to the third shel Solution Obvious first to third shell. E is proportional to [1/n1^2 -1/n2^2] [1/n1^2 -1/n2^2] is more when electron moves from the first to the third shel.