Show that the wavelength of electromagnetic radiation is equal to the de-Broglie wavelength of its quantum (photon).

The momentum of an electromagnetic wave of frequency V, wavelength λ is given by

p = hv /c = h / λ

or

λ = h/p

de broglie wavelength of proton, λ = h/p

h/p = h/ (hv/c) = c/v

Thus, wavelength of electromagnetic radiation is equal to the de-Broglie wavelength.