The Neko Seesaw Game - Presented by the Infinite Cat Project

Upon exposing a metallic surface to electromagnetic radiation that is above the threshold frequency (which is specific to the type of surface and material), the photons are absorbed and current is produced. No electrons are emitted for radiation with a frequency below that of the threshold, as the electrons are unable to gain sufficient energy to overcome the electrostatic barrier presented by the termination of the crystalline surface (the material's work function). In 1905 it was known that the energy of the photoelectrons increased with increasing frequency of incident light, but the manner of the increase was not experimentally determined to be linear until 1915 when Robert Andrews Millikan showed that Einstein was correct.[2]
By conservation of energy, the energy of the photon is absorbed by the electron and, if sufficient, the electron can escape from the material with a finite kinetic energy. A single photon can only eject a single electron, as the energy of one photon may only be absorbed by one electron. The electrons that are emitted are often termed photoelectrons.
The photoelectric effect helped further wave-particle duality, whereby physical systems (such as photons, in this case) display both wave-like and particle-like properties and behaviours, a concept that was used by the creators of quantum mechanics. The photoelectric effect was explained mathematically by Albert Einstein, who extended the work on quanta developed by Max Planck.