The electron, its isolation and measurement and the determination of some of its properties

by Robert Andrews Millikan

in which

is tine energy absorbed by the electron from the light wave or light quantum, for, according to the assumption it was the whole energy contained in that quantum,

is the work necessary to get the electron out of the metal, and

is the energy with which it leaves the surface—an energy evidently measured by the product of its charge

by the potential difference