Photoelectric Effect

Work function Wavelength of incident radiation Maximum KE of liberated electron

The Photoelectric Effect is a phenomena in which an electron is emitted from a metallic surface when a beam of light touches it. Photoelectrons are the electrons that are released from the surface.

• Photoelectric current is the term used to describe the current generated by photoelectrons.
• The photoelectric effect is caused, in part, by the energy of light being absorbed by the electrons on the metal surface.
• The forces holding the electrons to the metal nuclei are overcome by the electrons using this light energy.
• Heinrich Rudolf Hertz, a German scientist, made the discovery of the photoelectric effect in 1887.
• He discovered that UV illumination of the emitter plate promoted high-voltage sparks over the detector loop.
• He came to the conclusion that light aided in some electron emission as a result of this discovery.
• This led scientists to the conclusion that when the right kind of radiation strikes a metal surface, certain electrons nearby can absorb enough energy from the radiation to repel the positive ions that are attracted to the surface of the material.
• In 1988, Wilhelm Hallwachs made the observation that the divergence of gold leaf is reduced by ultraviolet light shining on a negatively charged zinc plate linked to an electroscope.
• He came to the conclusion that a negatively charged zinc plate releases negatively charged particles when exposed to ultraviolet light.
• The photoelectrons that are released are caused by the action of light.