Suppose a charged particle kept in magnetic field. There are two observers watching it. If one of the observer suddenly starts moving then I know that it will appear to him that the charged particle is moving in the opposite direction and he is going to see the particle move around in a loop.
But what about the stationary observer he is still at rest and for him the particle is going to be at rest forever not the slightest affected by the magnetic field.
So what is the particle actually doing?
Any help is appreciated :)
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