Should the energy of a photon be called its kinetic energy or its internal energy?
Relativistic equation of energy :
`E^2 = p^2c^2 + m^2c^4` ....(1)
Here, p2c2 = kinetic energy of photon
m02c4 = internal energy of photon
We know photons have zero rest mass. Therefore, m0 = 0. Substituting the value of m0 = 0 in equation (1), we get : `E = pc`
Thus, the energy of a photon should be called its kinetic energy.