Electric field inside a conducting wire

  • #1

Main Question or Discussion Point

The electric field in a 2.5mm×2.5mm square aluminum wire is 2.1×10−2 V/m . What is the current in the wire?
The answer is I=4.65A.

But my question is according to Gauss law, the electric field inside the conductor is zero. then how come this question says
"The electric field in a 2.5mm×2.5mm square aluminum wire is 2.1×10−2 V/m "
 

Answers and Replies

  • #2
cnh1995
Homework Helper
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according to Gauss law, the electric field inside the conductor is zero
This is true only in electrostatic equilibrium. When you connect a voltage source across a conductor, there will be a non-zero electric field inside the conductor and it will drive a current through the conductor such that current density J=σ*E, where σ is the conductivity of the material.
 
Last edited:
  • #3
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according to Gauss law, the electric field inside the conductor is zero
The response from @cnh1995 is correct, but may have left you wondering if Gauss law is violated. It is not. Gauss's law tells us that if there is no charge inside a surface then the net flux is 0. Inside a conducting wire there is flux, but there is just as much flux going in and going out, so the net flux is zero. Gauss's law holds.
 
  • #4
Thanks a lot for clearing my confusion.
 

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