Magnetic Fields

Magnetic Force on a

Current-Carrying Conductor

 Electric current is a flow of moving charges.

Notice that the direction of the Force is the same if we think of a current as positive charges moving in the direction of the current I or if we think of a current as negative charges moving in the direction opposite to that of the current I. Remember,

F = q v x B

For the two different interpretations of current, the direction of the velocity changes but there is also a change in sign of the charge q.

Force on a Charge

Torque on a Current-Carrying Loop

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(c) Doug Davis, 2002; all rights reserved