Conversion of Magnetic Forces to Electric Forces by Special Relativity Transform In this animation we have negative charge flow counter-clockwise in a rectangular loop of wire as well as a negatively charged test particle, qtest, moving to the left at speed vtest. Since the test charge is just below the top side of the wire loop, the magnetic field from the wire would normally cause a magnetic force on the test charge in the upward direction. However, if we use special relativity to transform both the positive and negative charges in the wire so that the test charge is stationary, then the magnetic force will disappear. The magnetic force is replaced by an electric force that, when transformed back to the laboratory frame, is exactly the same as the previous magnetic force. This demonstration of the way that magnetic forces can be transformed to electric forces is usually done by considering an infinitely long straight wire. A problem with that approach is that there is no way of seeing how the total numbers of positive and negative charges are conserved. In this animation it is seen that the loss of charge in the top side of the loop is exactly compensated by a gain of charge in the bottom side. The mystery is what, DURING the transformation, causes a fraction of the negative charges to move from top side to bottom side? Since changing speed involves acceleration of all of the charges, perhaps this riddle can be solved by general relativity.
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betaTest betaI nC0 Single Step Show Positive Charges Show Negative Charges