Question

Write the basic features of the photon picture of electromagnetic radiation on which Einstein’s photoelectric equation is based.

Answer 1

In order to solve this question, we should know that the term photon represents the particle nature of light and here we will discuss about various important properties of photon governing particle nature of light and by use of this Einstein photoelectric effect is explained.

Complete answer:
Particle theory of light suggests that light is made up of particles called photons and the basic features of photons are listed as,
(a) Light consist of particles called photon which travels in free space with the speed of light as $c = 3 \times {10^8}\,m{s^{ - 2}}$

(b) Each photon has energy of $E = h\nu$ where h is Planck constant and $\nu$ is frequency of the electromagnetic radiation. and each photon has a momentum associated with it as $p = \dfrac{E}{c}$ where $P, E$ represent momentum and energy of the photon.

(c) Whenever a photon interacts with another particle such as an electron or proton it transfers its energy to these particles and these particles gain kinetic energy and there is no time lapse between collision of photon and other particle and transfer of kinetic energy.

Having such important properties of photon picture of electromagnetic radiation, Einstein photoelectric equation which is written as $h\nu = W + K.E$ where $E = h\nu$ is the energy of the photon, $W$ represent work function of the metal on which photon falls, $K.E$ represent the kinetic energy of the electron gained as photon interact with matter it transfer its energy. This phenomenon of inducing current is due to the particle nature of light and known as photoelectric effect.

Note: It should be remembered that, photons are imagined as bundle of packets which travel in free space with speed of light and if light has n number of photons in it then, its total energy will be simple n times the energy of individual photon and written as $E = nh\nu$.