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Do electric fields also generate smaller electric fields?

  1. Mar 4, 2010 #1
    *first time posting on here*

    Hi, firstly I am a high school junior taking physics and I find it very interesting and plan to major in it. Now, today my teacher was explaining electric fields and said that all charged objects generate them around themselves. He then said that fields themselves were charged. After thinking about it, I realized that if this were true, then there should be electric fields made by other fields, ad infinitum. Firstly, is my reasoning correct, and secondly, if it is not, what was my mistake?

    thanks in advance
  2. jcsd
  3. Mar 4, 2010 #2

    Doc Al

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    Staff: Mentor

    You need to ask him to clarify what he meant. Fields don't have charge.
  4. Mar 4, 2010 #3
    he showed us a diagram where there was a positively charged rod near a negatively charged rod. he then drew field lines, and the ones on the outside were curved outward because they were repelling, according to him, which I assume means they have charge. Exactly where is the mistake in this reasoning?
  5. Mar 4, 2010 #4

    Doc Al

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    Staff: Mentor

    The first mistake is the statement that the field lines are repelling each other. That seems an odd thing to say. I can see how that might lead you to conclude that fields have charge, if you think that only charges can repel.

    Charges are surrounded by electric (and, if moving, magnetic) fields, but the fields themselves do not contain charges.
  6. Mar 4, 2010 #5


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    But, in a manner that you are not intending, the fields do generate secondary fields when they interact with matter. For example, if I induce an electric field across a dielectric, I cause polarization within the dielectric. That is, the molecules inside the dielectric become dipoles, the charges in the molecules shift slightly so that there is a local positive and local negative charge. This causes a secondary electric field and, when added to the original field that I induced, gives you the total field that you observe when you place the dielectric into the original field.

    So fields can induce secondary fields, which induce tertiary fields, and so forth. Not because the fields are charged, but because any existing charges in the environment subjected to these fields respond to the fields and can create new fields.
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