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I don't understand electric fields.

  1. Oct 5, 2013 #1
    According to my textbook, the electrical field is defined as E = F/q where q --> 0, because we want the test charge to affect the other charges around it in the least possible way. It then goes on to say that qE = F is true for charges not strong enough to move the other charges. Why is that, if the electrical field was defined very specifically? Why can I use qE = F for all charges, as if the q wasn't a test charge all along?
  2. jcsd
  3. Oct 5, 2013 #2
    They just define it that way to say that the charge q is small enough not to affect the electric field already in place. If the electric field generated by q was comparable to E, then they would interact differently than they do in this situation.
  4. Oct 6, 2013 #3
    yes.he is correct. furthermore,for proper studies an extra factor which is proportional to 1by r may arise..due to the disturbace by photon on the charge particle..
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