The photoelectric effect is a phenomenon that occurs when light shined onto a metal surface causes the ejection of electrons from that metal. It was observed that only certain frequencies of light are able to cause the ejection of electrons.
This minimum frequency needed to cause electron ejection is referred to as the threshold frequency.
Classical physics was unable to explain the photoelectric effect. If classical physics applied to this situation, the electron in the metal could eventually collect enough energy to be ejected from the surface even if the incoming light was of low frequency.
The photoelectric effect is applied in devices called photoelectric cells, which are commonly found in everyday items such as a calculator which uses the energy of light to generate electricity.
Light has properties of both a wave and a particle.
The photoelectric effect is produced by light striking a metal and dislodging electrons form the surface of the metal.