Newtonian mechanics is considered an extremely valid "approximation" for large objects whose speed relatively small (compared to the speed of light). But, we generally acknowledge that they aren't "true," even though they are still useful. My question is are Maxwell's equations similar in this respect? In other words, I know that at a certain scale they are useful, just like Newtonian mechanics is, but I was wondering if they are still "true" at the quantum scale. There are times when we treat a photon as a wave and times when we treat it as a particle. When we are treating individual photons as waves do Maxwell's equations still hold? Or are they just approximations for large amounts of photons?