Postby TGTS0907129» Force between currents

Describe the force between currents

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When parallel current-carrying conductors are adjacent, each exerts a force on the other. We may think of one of the currents, with its accompanying field, as being situated in the field caused by the other current. This will result in a force between the current-carrying conductors. In terms of the efflux picture, we visualized the effects as if they were caused by the lines acting like stretched rubber bands, with tension in the direction of their lengths. Hence currents in the direction produce an attractive force. We may visualized this in another manner by noting that the field between the wires is much weaker than the field between the wires is much weaker than the field outside the wires,  and hence tend to move away from the strong field and toward  the weaker one. Unlike the rubber-band analogy, the line lines are visualized as having a repulsive force in a direction perpendicular to their lengths. This assists us in seeing why currents in opposite direpulsion, produce a force of repulsion. Since the two currents in this case combine to produce a strong field between the wires, it follows that the wires are repelled from each other, since they tend to move from the stronger toward, since they tend to move from the strong toward the weaker fields.

A measure of the forces between parallel current-carrying conductors may be obtained the expression for the field near a long straight conductor. Field of current IA in wire A is given by
                       


The force on current IB in wire Bis therefore
            


The relation expressed may be used to define the mks unit of current: the ampere is a current that when it is maintained in two infinitely long conductors, parallel to each other and 1 m apart in a vacuum. Will cause a force on each conductors of exactly 2 × 10-7 newton per meter length. The numbers chosen in this chose in the definition are such as to make the unit thus defined essentially the same as the ampere defined by other methods.
 

By TGTT30071258 on 9/21/2015 9:59:56 PM
TGTS0907129 on 9/21/2015 9:48:57 PM
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