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Electric fields vs magnetic fields?

  1. Feb 24, 2014 #1
    Electric fields vs magnetic fields???

    Ok, so in class last week, I had asked my professor about using the Lorentz Force Law to solve a particular problem. When he responded with "we only have a magnetic force from the current in the wire, so we don't have to worry about an electric field," that completely threw me for a loop.

    A quote directly from our course's textbook, "All moving charged particles create magnetic fields... This is in addition to the electric field that is always present surrounding charged particles." A quote from another textbook, "A moving charge always has both a magnetic and electric field." Based on these statements and other external materials I read regarding the matter, I thought that whenever you have a magnetic field (excluding permanent magnets), you always have an electric field? I know I have read this in at least one or two other places as well, but maybe I'm just missing something here? If someone could clarify, I'd appreciate it.
  2. jcsd
  3. Feb 24, 2014 #2


    Staff: Mentor

    The wire is uncharged. All of the electric fields of the electrons are canceled out by the electric fields of the protons. However, since the electrons are moving and the protons are not the magnetic field of the electrons is not canceled out. Therefore, you get a magnetic field and no electric field.
  4. Feb 24, 2014 #3

    Vanadium 50

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    Your wire is uncharged, right? Then there is no net electric field from it.
  5. Feb 24, 2014 #4
    Ok, I wasn't aware the no matter how much current flows through the wire, the proton to electron ratio is still always balanced. That was where my problem was... well that and misunderstanding the statements regarding charges and their fields. Thanks.
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