Volume 22: Pages 427-431, 2009
Space contraction and the angular dependence of the force due to a current on a moving charge
Jair Lucinda 1
1Departamento de Física, Universidade Federal do Paraná, CP 19044, CEP 81531-990, Curitiba, Paraná, Brazil
An analysis within the framework of special relativity, without alternative structures or new speculations, bears the conclusion that if the velocity of a charge is not parallel to the net current flow along a rectilinear and neutral wire, then this charge is under action of a force that depends, essentially, on the angle between its velocity and the mean drift velocity of the electrons. In this case, the effect due to the steady current on the moving charge does not furnish the magnetic field that one detects with a magnet or a compass. Further, the force on this charge is proportional to the net charge density, which is a consequence of space contraction from the standpoint of its rest frame. Therefore, contrary to what the usual physical intuition appears to demand, there is no interaction when the test charge moves perpendicularly to a steady current flowing along a rectilinear electrically neutral wire.
Keywords: Current-Bearing Wire, Space Contraction, Magnetic Force, Electric Force, Steady Current Field
Received: October 1, 2008; Accepted: May 13, 2009; Published Online: September 11, 2009