Plank-Einstein relationship e=hv (1) The proportionality constant h relating the energy of a photon to its frequency turned out to be the one introduced by Plank in his theory. so-called as Plank constant. The particulate interpretation of the photoelectric effect is straightforward. Each photon absorbed by a metal can lead to emission of one electron providing that the energy of the photon, when transferred to the electron, is sufficient to enable the electron to escapePlank-Einstein relationship E = h (1) The proportionality constant h relating the energy of a photon to its frequency turned out to be the one introduced by Plank in his theory. So-called as Plank constant. The particulate interpretation of the photoelectric effect is straightforward. Each photon absorbed by a metal can lead to emission of one electron providing that the energy of the photon, when transferred to the electron, is sufficient to enable the electron to escape