Since Newton's law of gravitation can be gotten out of Einstein's field equatonsequations as an approximation, I was wondering whether the same applies for the electromagnetic force being the exchange of virtual photons. Is there an equation governing the force from the exchange of photonsvirtual photons? Are there any links which would show how the Coulomb force comes out of the equations for virtual photon exchange? I know that my question is somewhat similar to the one posted here The exchange of photons gives rise to the electromagnetic force, but it doesn't really have an answer to my question specifically.