posted by Ella .
An electron de-excites from the fourth quantum level, to the third and then directly to the ground state. Two photons are emitted. How does the sum of their frequencies compare with the frequency of the single photon that would be emitted by de-excitation from the fourth level directly to the ground state?
Energy is the same as frequency.
E1+ E2 = E3
F1 + F2 = F3