Final answer:
The photoelectric effect refers to the ejection of electrons from a metal surface when hit with light of sufficient energy, a principle essential for the operation of solar cells.
Step-by-step explanation:
The photoelectric effect is the phenomenon by which electrons are ejected from the surface of a metal when it is exposed to light of sufficient energy. This occurrence contradicts classical predictions, which anticipated that the light's intensity (rather than its frequency) would be the determining factor for electron emission. However, in the quantum explanation of this phenomenon, it is understood that no electrons are ejected if the energy of the incoming photons is less than the material's threshold energy, regardless of the light's intensity. The photoelectric effect is crucial for understanding how devices like solar cells operate. When such cells are exposed to sunlight, they convert absorbed photons into electrical energy, which is a direct application of the photoelectric effect in the generation of electrical power.