A deliberation on the limits of the validity of Newton's third law in Electromagnetism

Abstract

It is shown that as Newton's third law holds in static discussions of Electromagnetism it holds also in dynamic discussions of it, ie where the motion of electric charge in the magnetic field arising from the magnetic static (or magnetostatic) poles is under consideration. In addition, it is shown that in this recent case the forces of action and reaction are not collinear. In other words as we know there is some force exerted on a current-carrying wire in the magnetic field of a magnet. It is shown that this magnet is in fact the same enlarged magnetic needle in Oersted's experiment, and then there exists also some force exerted on the magnet due to the electric current in the wire. These two action and reaction forces are in opposite directions but are not collinear.

KEYWORDS: Newton ; third ; law ; action ; reaction ; electromagnetism ; electrostatics ; magnetostatics ; electrodynamics ; magnetodynamics ; Biot ; Savart ; Oersted

PACS: 41.90.+e 

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