So I was thinking about E&M today, and specifically, how E&M relates to the ideas of relativity. Specifically, that magnetism is induced by a change in an electric field and vice versa. This got me thinking of some scenarios. In each, you have a particle emitting a constant magnetic field and another emitting a constant electric field. In the first scenario, you have one particle stationary at one point. The second particle is at some radius from it. A centripetal force is applied on the second particle which induces circular movement. The particles now "see" each other moving, and their respective fields changing, and the two particles begin to exert a force on each other. This is all correct, right? I've only taken freshman level E/M courses really, which is why I could use some help. The second scenario is a bit trickier. The two particles are at the same position on a rotating plate. From an outsider's perspective, the second particle seems to be rotating around the first particle, which is stationary but spinning in the center of the disk. The observer notices, for example, if the rotating particle is electrically charged, that it begins to create a magnetic field due to the changing electric field. However, the particles are not attracted to each other because, all though there is circular motion of one, the other particle is in the exact same reference frame and does not "see" any movement from the other particle. The third scenario involves the first particle at the center of our rotating disk and the second particle just outside of it. An outside observer sees no movement of either particle besides the rotation of particle one. The observer measures no INDUCED electric or magnetic fields. However, the first particle "sees" the second particle rotating around it, as a person on a rotating disk might see a person outside of it and perceives an induced field. There is now a force between them which the observer obviously sees and interprets as a mysterious force. Are any of these right? Or do I have a fundamental misunderstanding of this idea in E/M? I could use some help/refining.