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A steady current I flows through a circular loop of wire. As the current travels around the loop, the direction of the current density j keeps changing while the magnitude of I stays the same. What is mainly responsible for continually redirecting the current along the bent wire?

1. the electric field produced by charges that accumulate on the surface of the wire
2. the source of emf
3. the charges just behind a given segment of wire pushing it forward by repulsion
4. the charges lying ahead of the segment

Correct answer: the electric field produced by charges that accumulate on the surface of the wire

Solution

In a steady current, charges build up on the surface of the bent conductor and create an internal electric field that has the right direction at each point to steer the current along the wire.

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