Electric field around a current carrying wire

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Discussion Overview

The discussion centers around the existence of an electric field around a current-carrying wire, particularly in the context of direct current (DC) and high voltage direct current (HVDC) transmission lines. Participants explore theoretical and practical implications, including the effects of capacitance and the conditions under which an electric field may or may not be present.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants assert that no electric field exists around a DC carrying wire, citing the wire's overall electrical neutrality and the absence of a radial electric field.
  • Others introduce the concept of parasitic and self-capacitance, suggesting that a wire can act as one plate of a capacitor, potentially leading to a weak electric field, especially at higher voltages.
  • A participant mentions the phenomenon of corona discharges around HVDC lines, questioning whether a detectable electric field exists around low power DC wires.
  • Some participants emphasize the distinction between static and dynamic conditions, noting that a wire carrying DC current has a magnetic field due to the current but may have varying electric fields depending on the wire's net charge.
  • There is a suggestion that the idealization of wires as having no capacitance or resistance contributes to the belief that they do not create external electric fields.

Areas of Agreement / Disagreement

Participants express differing views on the existence and nature of electric fields around current-carrying wires. There is no consensus on whether an electric field is present in low power DC wires, and the discussion remains unresolved regarding the implications of capacitance and charge on the electric field.

Contextual Notes

Limitations include assumptions about ideal wire behavior, the dependence on voltage levels, and the distinction between static and dynamic electric fields. The discussion does not resolve the mathematical or physical implications of these factors.

arul_k
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It is generally thought that no electric field exists around and outside of a current (DC) carrying wire as the electric field has no radial component and the wire as a whole remains electrically neutral.

However i came across information on the net regarding high voltage (HVDC) transmission lines that stated the existence of an electric field and its effects such as corona dicharges around these power lines.

I would like to know whether an electric field exists around low power DC wires. Is it just that the field is too weak to detect?
 
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You can consider a wire to be one plate of a capacitor with ground. Try googling "parasitic capacitance" and "self capacitance". As a capacitor it can become charged up and then have an E-field, but as you say this effect is small for low voltages.
 
DaleSpam said:
You can consider a wire to be one plate of a capacitor with ground. Try googling "parasitic capacitance" and "self capacitance". As a capacitor it can become charged up and then have an E-field, but as you say this effect is small for low voltages.


I am also aware of a continuous electric discharge (similar to lightening) that is possible near HVDC lines. If the electric field is due to a build up of charge then a continuous discharge would not be possible. From what I have come across on the net, current flowing through a wire creats no external electric filed.
 
arul_k said:
From what I have come across on the net, current flowing through a wire creats no external electric filed.
Only because a wire is usually idealized to have no capacitance and no resistance.
 
We are confusing statics and dynamics. A wire carrying a dc current will have a manetic field only due to the current. It can have any electric field positive negative or zero depending on the net charge of the wire
 
Antiphon said:
We are confusing statics and dynamics. A wire carrying a dc current will have a manetic field only due to the current. It can have any electric field positive negative or zero depending on the net charge of the wire


The wire is electrostatically neutral to begin with. Do you mean that passing a current through a wire will give it a static charge
 

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