Electric field inside a conducting wire

Click For Summary

Discussion Overview

The discussion revolves around the electric field inside a conducting wire, specifically addressing a scenario where a non-zero electric field is reported in a square aluminum wire while referencing Gauss's law, which states that the electric field inside a conductor is zero in electrostatic equilibrium.

Discussion Character

  • Debate/contested

Main Points Raised

  • Post 1 questions the reported electric field of 2.1×10−2 V/m in the wire, citing Gauss's law which states that the electric field inside a conductor is zero.
  • Post 2 clarifies that Gauss's law applies only in electrostatic equilibrium and that a non-zero electric field exists when a voltage source is connected, driving a current through the conductor.
  • Post 3 supports the previous point, explaining that while there is flux inside the wire, it does not violate Gauss's law, as the net flux remains zero due to equal amounts of flux entering and exiting the surface.
  • Post 4 expresses gratitude for the clarification provided in the discussion.

Areas of Agreement / Disagreement

Participants appear to agree on the distinction between electrostatic conditions and those involving a voltage source, but there is an ongoing debate regarding the implications of Gauss's law in this context.

Contextual Notes

The discussion highlights the conditions under which Gauss's law applies and the nature of electric fields in conductors when a current is present, but does not resolve the apparent contradiction regarding the reported electric field value.

Mohammed Shoaib
Messages
17
Reaction score
0
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 "
 
Physics news on Phys.org
Mohammed Shoaib said:
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:
Mohammed Shoaib said:
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.
 
  • Like
Likes   Reactions: Mohammed Shoaib and cnh1995
Thanks a lot for clearing my confusion.
 

Similar threads

  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 3 ·
Replies
3
Views
999
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 9 ·
Replies
9
Views
3K
  • · Replies 7 ·
Replies
7
Views
1K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 10 ·
Replies
10
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 15 ·
Replies
15
Views
2K