Thephotoelectric effectis the observation that manymetalsemitelectronswhenlightshines upon them. Electrons emitted in this manner may be calledphotoelectrons.
According toclassical electromagnetictheory, this effect can be attributed to the transfer ofenergyfrom the light to an electron in the metal. From this perspective, an alteration in either theamplitudeorwavelengthof light would induce changes in the rate of emission of electrons from the metal. Furthermore, according to this theory, a sufficiently dim light would be expected to show a lag time between the initial shining of its light and the subsequent emission of an electron. However, the experimental results did not correlate with either of the two predictions made by this theory.