What the is rest mass energy of a photon?

What is the rest mass of a photon?

What is the rest mass of a photons?

A gamma ray photon creates an electron positron pair. If the rest mass energy of an electron is 0.5 MeV and the total kinetic energy of the electron positron pair is 0.78 MeV, then the energy of the gamma ray photon must be

A gamma ray photon creates an electron-positron pair. If the rest mass energy of an electron is 0.5 MeV and the total K.E. of the electron-position pair is 0.78 MeV , then the energy of the gamma ray photon must be.

The rest mass energy of electron is