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Electric field around a current carrying wire

  1. May 7, 2010 #1
    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 existance 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?
  2. jcsd
  3. May 7, 2010 #2


    Staff: Mentor

    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.
  4. May 7, 2010 #3

    I am also aware of a continous 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 continous discharge would not be possible. From what I have come across on the net, current flowing through a wire creats no external electric filed.
  5. May 7, 2010 #4


    Staff: Mentor

    Only because a wire is usually idealized to have no capacitance and no resistance.
  6. May 7, 2010 #5
    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
  7. May 8, 2010 #6

    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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