I did more than one course of classical electromagnetism in college. Recently, however, after reading "How Relativity Connects Electric and Magnetic Fields" (http://galileo.phys.virginia.edu/classes/252/rel_el_mag.html) I was astounded to realize how little I knew about it! In college (if I remember well) never was mentioned the relationship between Maxwell's equations and relativity.(adsbygoogle = window.adsbygoogle || []).push({});

If we have two charges A and B that move at the same speed v, I always thought that there would be no magnetic field between them because the relative velocity between A and B is zero. I never noticed that the velocity v in the Maxwell equations were ABSOLUTE. However after reading the article I realized that from the viewpoint of an observer at rest there is a magnetic attraction force, but from the viewpoint of an observer that also moves with velocity v, there is none!

What I donâ€™t understand is how to explain such obvious discrepancy without resorting to the relativity theory (that came much later) and how can someone teach electromagnetism without relativity ...

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# How Maxwell's equations explain the Lorentz contraction?

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