He introduced the idea that an electron can drop from a higher energy orbit to a lower one.

When an electron drops back down to a lower level, it releases the energy as radiation.

Luminescence is the process whereby light is emitted when the electron drops to a lower energy level.

Balmer-alpha occurs when the electron drops from the second excited state to the first (and has nothing to do with Steve or thrown chairs).

Lyman-alpha emissions occur when the electron drops from the first excited state back to the ground.

Eventually, the promoted electron will drop back down to its ground-state orbital.

The wavelength of light is determined by the amount of energy released when the electron drops to a lower orbit.

The electron will eventually lose energy (by releasing a photon) and drop into the lower orbital.

When the electron drops back down, it emits a photon.

An electron that loses energy to a photon drops inward from the outside of the cloud.