How does the exchange of virtual photons attract opposite charges and repel like-charges?

Question

Any information on this would be greatly appreciated.

Answer 1

In the interaction of electrons with other charged particles, say protons, mesons, etc., the explanation is just as in the classical theory: The interaction beteen the particle and the electromagnetic field is proportional to the charge of the particle. In the exchange of a photon between an electron and another particle two such terms are multiplied, so that the interaction involves the product of the two charges,so that the sign will be automatically different if the charges are the same or different.

In the Dirac hole theory, a positron is the absence of an electron in a sea of electrons in negative energy states, so it will behave as if it were an electron with positive charge.