Photoelectric Effect - max kinetic energy of an ejected electron

Description

The photoelectric effect is the observation that many metals emit electrons when light shines upon them. Electrons emitted in this manner may be called photoelectrons.
According to classical electromagnetic theory, this effect can be attributed to the transfer of energy from the light to an electron in the metal. From this perspective, an alteration in either the amplitude or wavelength of 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.
Kinetic energy is positive, so we must have f > f_0 for the photoelectric effect to occur

Related formulas

Variables

Kmaxmaximum kinetic energy of an ejected electron (joule)
hPlanck constant
ffrequency of the incident photon (Hz)
f0threshold frequency for the metal (Hz)