Write Einstein’s photoelectric equation and point out any two characteristic properties of photons on which this equation is based. Briefly explain the three observed features which can be explained by this equation. 

Einstein’s photoelectric equation is given by, 

                   

Characteristic property of photons:

i) Energy of the photon is directly proportional to the frequency.

ii) The total energy and momentum of the system of two constituent particles remain constant in a photon-electron collision.

Three observed features of the photoelectric effect are:

i) When the frequency of the incident photon increases, the kinetic energy of emitted electron increases. Kinetic energy does not have any effect on the Intensity of radiation.

ii) When the intensity of incident light increases, the number of incident photons increases. The increase in intensity will increase the number of ejected electrons. That is, photocurrent will increase with the increase in intensity. Frequency has no effect on photocurrent.

iii) When the energy of an incident photon is greater than the work function, the photoelectron is immediately ejected. Thus, there is no time lag between the incidence of light and the emission of photoelectrons.