(e) Intensity :The power (energy) associated with the radiation field is measured in terms of intensity I. It is defined in terms of watt/cm². It is related to the electric field associated with em wave given by

...........................(1.3)

where is the velocity of propagation of the wave and is the electrical permittivity of the medium through which the wave is propagating.

(f) Propagation of EM wave: Electromagnetic waves obeys the Maxwell’s equations.

While talking about the propagation or the transmission of light through a medium without undergoing significant attenuation, then the medium is a dielectric. The Maxwell’s equations for a dielectric medium are given below:

..................(1.4)