Frequency Wavelength relation

C = νλ

        Here 'ν' represent frequency of radiation , λ' represent the wavelength of the radiations and 'C' represent the speed of light in vacuum(i.e. 299,792,458).

             This equation is only applicable to electromagnetic radiation.In other cases 'C' should be replaced by the velocity of the wave

Planck's energy frecuency relation

E=hν

Here ‘ν’ is the frequency of radiation, ‘h’ is Plank’s constant (6.62606957x10^-34J.s), and ‘E’ is the energy of a single photon in the radiation.

Since 'λν=C' this equation can also be written as

E=hC/λ

Mass–energy equivalence

E=ΔMC² 

^{Here ‘ΔM ‘ means change in mass, ’c’ is the speed of light in vacuum(299,792,458m/s), and ‘E’ is the energy produced.}

            ^{Mass-energy equivalence was proposed by Albert Einstein in 1905 This equation is based on a concept that mass of a body is the measure of its energy content.}