How is light produced?
Before getting into depth of production of light, let us define the term quanta or quantum.A quanta is the minimum amount of a given physical unit.It is the smallest amount of a given physical entity such as energy or matter.The quantum of light or as for that matter any electromagnetic radiation is known as a "photon".The current understanding of optics and formation of light is due to the efforts of Max Planck and Albert Einstein.
The electron in the atom acquires the energy of a photon , this energy acquired by the electron is greater than the work function of the electron in the atom.This helps in the electron overcoming the force which binds the electron to the atom , which in turn causes it to be ejected out , provided the energy possessed by these photons is greater than the work function. This results in the electron gaining kinetic energy.
With an increase in the intensity of the light rays more electrons are ejected out due to the presence of more photons. The energy acquired by the electron depends on the energy of the photon and has no relation with the light ray.
The maximum amount of kinetic energy possessed by the electron is given by -
K.max = hf-φ
K.max is the maximum kinetic energy of the electron
h is the Planck constant
f is the frequency of the incident photon
Φ is the work function