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Electromagnetic field

  1. Sep 2, 2008 #1
    Four interesting questions:

    1: Is there a maximum range of a given electromagnetic field?

    2: Is there a maximum strength of an electromagnetic field?

    3: If the maximum electric field or magnetic field different from each other?

    4: Can you make an electric or magnetic field so strong or localized that light can't escape?
  2. jcsd
  3. Sep 2, 2008 #2


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    1) Not really, but it depends what you mean by range. Any small perturbation to the field must have time to propogate (it moves at speed c in vacuum). There is of course the size of the visible universe which is sort of the maximum distance observers here on earth can see, and I guess that would be a practical limit. So I mean theres nothing stopping you from having a universe sized blackhole or something with a huge EM field everywhere *in principle*. In practise fields tend to die off like R^2, so physically we tend to think that say a battery on earth won't really affect Mars (even though the correct answer will be some obscene decimal place).

    2) No, though again probably on the order of the energy content of the visible universe for practical purposes.

    3) Frame dependant question.

    4) Yes according to GR.
  4. Sep 2, 2008 #3
    Thanks for your input. Given its strengh dies off quite dramatically, I guess those beings on alpha centauri don't care what I do with a bar magnet, lol.

    I was thinking can magnetic fields get so strong they can squish protons and electrons out of existence? If not, maybe that's the strongest they can get because unless the bosons carry the load what will the source of the charge. Anyway, hmmm maybe we can be the first to hypotesize a magnetic black hole ^^.
  5. Sep 2, 2008 #4


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  6. Sep 2, 2008 #5


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    Light is an electromagnetic wave, so other electromagnetic waves can effect each other in the same way that waves on a pond effect one another: by constructively or destructively interfering with each other. Being 'strong' is not the main point.
  7. Sep 2, 2008 #6
    Oh you have a good point there, depending on the angle and how light it bent it may cause inference or affect it in other ways so as not to get swallowed up by an magnetic force of ridiculously high strength, although I suppose particles wouldn't be too fortunate unless they find a way to exhibit wave-like aspects as well. Maybe a lot of charged particles may heat up to super high temps and dance around the poles like a hyper version of aurora's on earth.
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