How was it proved that electromagnetic radiation is a form of energy?

1 Answer
Sep 22, 2015

I'm sure there are many proofs and evidences of it, but one that springs to mind is the photo-electric effect


In the photo-electric effect, energy of photons (light particles which form part of the electromagnetic spectrum) are shone onto metals and eject electron from the metals and hence cause current to flow since current is a rate of flow of charge.

A certain minimum energy is required to eject electrons (dependant on the work function of the metal and related to the frequency of the incident light) and any excess energy is given as kinetic energy to the electrons.

#hf = W + 1/2 mv^2#