We now can use [the relativistic increase in charge density] for the positive … of our wire. These charges are at rest … , the positive charge density [is increased relativistically]. … [The forces in S and S' are equivalent after an additional relativistic transform.] … [p. 13-10] We have found that we get the … a coordinate system at rest with respect to … instance, the force [on the particle] was purely "magnetic," in … If we had chosen still another coordinate system, … are part of one physical phenomenon--the electromagnetic interactions …
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