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Existence of electromagnetic field

  1. Oct 17, 2010 #1
    Do electric and magnetic fields occur simultaneously in the same spot anywhere around the globe? (other than during solar flares)

    If the field is named "electromagnetic" wouldn't that means exactly this simultaneity?

    Thank you.
     
  2. jcsd
  3. Oct 17, 2010 #2

    sophiecentaur

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    You can have a constant magnetic field, on its own or an electric one. But, as soon as you start to change one, the other starts to appear. As you vary the current through a loop of wire, for instance, as well as the magnetic field, there is some electric field and the two fields start to radiate, carrying power - you have an electromagnetic wave. Same thing happens when you alternate the voltage on a dipole of wire - currents start to flow and magnetic fields are generated, again producing an electromagnetic wave.
    So, in answer to your question, yes- both electric and magnetic fields exist at the same time. When energy is radiated, the two fields are at right angles to each other and at right angles to the direction in which the energy flows.
     
  4. Oct 17, 2010 #3
    Thank you very much, Sophie.
    I am aware of the phenomenon and I apologize for not having been more explicit in my question.
    Trying again: Does anywhere (in atmosphere, space) exist naturally an electromagnetic field?
    More graphically: I have a closed loop, and am looking for an electromagnetic field to cut through. Is there such a place? Does electromagnetism surround us; is it a "standing" field?

    Thank you in advance.
     
  5. Oct 17, 2010 #4

    sophiecentaur

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    There's always the Earth's Magnetic Field. A fairly constant but low value of B. But you must have already thought of that, I'm sure.
    'Natural' E fields tend to get neutralised as charges flow. During Lightning storms, there can be very high fields - but I guess that's pretty obvious too.
    Otherwise, I really can't think of what you mean, in addition to those two.
     
  6. Oct 17, 2010 #5
    Thank you again.
    I just have a vague sense that there is an electromagnetic "potential" (not as in voltage, but as in "ready to manifest itself").
    Let's say that I drop or drag a ferromagnetic loop through space, atmosphere.
    Do I find charges on it?
     
  7. Oct 17, 2010 #6

    sophiecentaur

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    You could certainly expect to find the occasional charged particle. They are being thrown out by the Sun by the tonne all the time. On average, though, I would expect the same number of + and - charges.
     
  8. Oct 17, 2010 #7
    Thank you.
     
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