Einstein's interpretation
Planck proposed that electromagnetic radiation was not emitted and
absorbed continuously, but was emitted and absorbed in little bundles of
energy called quanta.
According to Planck, the energy of a quantum was proportional to the frequency of the wave.
Einstein accepted the notion of quanta and described light as a stream of photons (quanta), each travelling with the velocity of light. Einstein suggested that when a photon collides with an electron, the transfer of energy is an “all or nothing” process, i.e. the electron gets all the photon’s energy or none of it. If a photon gives all its energy to an electron, then it simply drops out of existence. The energy acquired by an electron may enable it to escape from the metal.
If a photon is to liberate an electron from a metal by the
photoelectric effect, its energy must exceed the work function of the
metal. Any excess energy which the photon has will appear as K.E. of the
electron which escapes.
Summary:
Einstein's Photoelectric Equation:
