12.5 T HE L INE S PECTRA OF THE H YDROGEN A TOM

. T HE L INE S PECTRA OF THE H YDROGEN A TOM According to the third postulate of Bohr’s model, when an atom makes a transition from the higher energy state with quantum number n i to the lower energy state with quantum number n f ( n f < n i ), the difference of energy is carried away by a photon of frequency + if such that