in some problems we use n2/n1= (poa- pa)/poa
but in some other cases we use n2/n1= (poa-pa)/pa
how to identify which one to use???
For which transition of He+ spectrum energy will be same as 2nd line of Balmer series of H spectrum?
What electronic transition in Li+2 produces the radiation of the same wave length as the first Line in the Lyman series of hydrogen?