So, I have been reading various sources, and I am getting a little confused as to what electrons, protons, and neutrons generate when moving. Do they generate photons, or a magnetic field? I guess what I am trying to understand is, do any of the particles listed above have a magnetic field when at rest, or just when in motion? I understand that they will emit EM at a certain velocity. I guess a second question would be, at what speed is it required in order for one electron to emit one photon.