What is the photoelectric effect?

The photoelectic effect is when photoelectrons are released from a metal that light is incident upon. The photoelectrons are only emitted when the photons of light are above a certain threshold frequency and energy (called the work function). The energy of the photoelectrons is equivalent to the gaps in electron energy levels of the atoms that compose the metal. Each photon above the work function produces exactly 1 photoelectron and any excess energy is given to the photoelectron in the form of kinetic energy. If the frequency of the light is below the threshold frequency then no photoelectrons are released.