The electron of a hydrogen atom is initially at the orbit n=4. If this electron first goes to the orbit n=3 and then to the orbit n=2 and then to the orbit n=1, how many photons are emitted during these transitions? How many photons are emitted if the electron directly falls from the orbit n=4 to the orbit n=1?
When an electron falls from a higher energy level to a lower energy level, its "lost" energy is emitted as a photon.
Photon emission during transition