ELECTRIC field due to a solenoid, or a current-carrying wire, or

Click For Summary

Discussion Overview

The discussion revolves around the electric fields produced by solenoids, current-carrying wires, and similar geometries, questioning the presence and characteristics of these fields in the context of steady versus changing currents. It explores theoretical aspects related to Maxwell's equations and the implications of charge distributions in conductive materials.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions why electric fields produced by steady currents are not discussed, suggesting that the presence of charges implies electric fields must exist.
  • Another participant cites Maxwell's equations, stating that without a changing magnetic field, the electric field has no curl and no divergence, leading to the conclusion that it is identically zero.
  • A different participant points out that current-carrying wires are electrically neutral due to equal amounts of positive and negative charge.
  • One participant elaborates on the conditions under which an electric field exists in a wire with conductivity, referencing Ohm's law, and questions whether the curl of the electric field is also zero in this scenario, given a constant charge density.

Areas of Agreement / Disagreement

The discussion contains multiple competing views regarding the existence and characteristics of electric fields in steady current scenarios, and it remains unresolved whether steady currents produce electric fields or not.

Contextual Notes

Participants reference Maxwell's equations and Ohm's law, but there are limitations in the assumptions made about charge distributions and the conditions under which electric fields may be present.

AxiomOfChoice
Messages
531
Reaction score
1
We always talk about the magnetic field produced by solenoids, straight wires of current, and rings of current, etc., but why do we never talk about the ELECTRIC fields produced by these geometries? I mean, there are CHARGES, right? So there must be electric fields present, right? Or am I wrong?

I know a CHANGING magnetic field produces an electric field, but why don't STEADY currents produce electric fields?
 
Physics news on Phys.org
This just follows directly from Maxwell's equations. With no changing B field the E field has no curl (Faraday's law), and with no net charge the E field has no divergence (Gauss' law). A field with no curl and no divergence is identically 0.
 
Current-carrying wires contain equal amounts of positive and negative charge, and are electrically neutral.
 
DaleSpam said:
. A field with no curl and no divergence is identically 0.

well, it may be constant in general. in case of wire with conductivity sigma, there is electric field inside the wire( given by ohm's law).. although if the current is steady and the conductivity uniform the divergence of the electric field becomes ZERO.
is the curl of electric field in this case also zero? i guess it should be because charge density in this case is constant with time everywhere.
 

Similar threads

  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 10 ·
Replies
10
Views
3K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 12 ·
Replies
12
Views
1K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
Replies
5
Views
2K
  • · Replies 9 ·
Replies
9
Views
4K
  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 5 ·
Replies
5
Views
2K