Describe and explain the photoelectric effect in terms of photons interacting with the surface of a metal.

The photoelectric effect is the emission of electrons from a metal surface when light is incident on it. When a photon (a light particle) hits the metal surface, it interacts with the metal's electrons. The energy of the photon is absorbed by the electron and if the energy is larger than some threshold energy ( the metal's work function) then the electron has enough energy to escape the metal's surface. Because this interaction is one to one, only the photon energy will determine the kinetic energy of the emmited electrons. The intensity of the light (determined by the number of photons) will not affect the kinetic energy of the electrons, only the number of electrons emmited. This means that low energy light (longer wavelengths) may not cause a metal to emmit electrons even if the intensity is very high, while high energy light (shorter wavelengths) could cause a metal to emmit electrons even if the intensity low.