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Q & A: Zero field inside a conductor?

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Most recent answer: 04/08/2014
Q:
Electric field inside a conductor is zero,so how current flows in conductor wire.
- Gagan Dubey (age 19)
Indore,India
A:

 That's a great question. You've noticed that something sounds inconsistent about the words we use to describe electrical conductance. The current would not keep flowing in an ordinary conductor (as distinct from a superconductor) without an electric field to keep pushing the electrons or other charge carriers. Otherwise they would slow down and stop due to collisions with other particles.  So the electric field isn't quite zero while the current keeps flowing.

On the other hand, if you put a conductor into an electric field, the charges flow to new places, making an electric field that cancels the original field. Unless there's some external source of an electromotive force (a changing magnetic field, chemical reactions in a battery,...) the field will fall to zero. So the situations where we say that the field in the conductor is zero are the ones like that- say where a piece of aluminum is placed near some static charges.  In a current-carrying wire, the field isn't zero.

Mike W.


(published on 04/08/2014)

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