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Dec11-12, 06:11 AM
P: 17,535
Quote Quote by Barry_G View Post
I don't see any reference to "source-free" equation or anything similar that would relate to zero net charge of a photon.
It was on that page that you were already given. Here is the direct link so you cannot miss it.

Btw, none of your questions are actually about photons. They are about classical EM. Specifically, you want to know how you can have EM fields in the absence of a charge. Maxwells equations in vacuum are the answer to that question.