Photoelectric Effect
Photoelectric Effect, formation and liberation of electrically charged particles in matter when it is irradiated by light or other electromagnetic radiation . The term photoelectric effect designates several types of related interactions. In the external photoelectric effect, electrons are liberated from the surface of a metallic conductor by absorbing energy from light shining on the metal's surface. The effect is applied in the photoelectric cell , in which the electrons liberated from one pole of the cell, the photocathode, migrate to the other pole, the anode, under the influence of an electric field. Study of the external photoelectric effect played an important role in the development of modern physics. Experiments beginning in 1887 showed that the external photoelectric effect had certain qualities that could not be explained by the theories of that time, in which light and all other electromagnetic radiation was considered to behave like waves. For example, as the light s