Write Einstein's photoelectric equation. State clearly how this equation is obtained using the photon picture of electromagnetic radiation. Write the three salient features observed in photoelectric effect which can be explained using this equation.

Einstein`s photoelectric equation is K(max)= 1/2 mv²=hv-W where, W is wave function1) A part of energy of the photon is used to liberate electron from the metal surface which is equal to work function W of the metal.2) The rest of the energy of the photon is used to get maximum kinetic energy k(max) to the emitted photo electron.