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Electric Field, Mass, Length

  1. Feb 1, 2007 #1
    I believe the following are all true for an observer in a different inertial frame :

    An object's length is contracted in the direction of its motion
    An object's mass increases under motion
    The strength of an electron's field is reduced in the direction of motion
    The strength of an electron's field is increased orthogonally to the direction of motion

    Have I got this right ? If so, is there a connection between the mass increase of an object and the field increase of an electron ?

  2. jcsd
  3. Feb 1, 2007 #2
    it isnt exactly mass increase.It is just energy that increases inertia
  4. Feb 2, 2007 #3

    Meir Achuz

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    Also the E and B fields of a moving electron are more complicated.
  5. Feb 2, 2007 #4
    Indeed, the important thing to remember about electromagnetism is that E and B are not true vectors. Their representations in terms of vector potential, A, are true however, and transform correctly under special relativity.
  6. Feb 2, 2007 #5
    Quite likely. There's a few published papers around discussing how when two (or more) charges are held nearby one another (changing the total energy of the system), you can even uncover the mechanism by which the weight of the system changes (basically, in an accelerated frame, each electron's asymetric field results in an unbalanced inertia-like force).
  7. Feb 2, 2007 #6


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    This is ambiguous as stated. Invariant mass does not change with motion. Relativistic mass does change with motion. See the usual FAQ's.
    Most likely wrong. If you have two observers at the same point in space-time that are moving relative to each other, the parallel component of the E-field will not change. You may be thinking of a different scenario. See for instance http://www.phys.ufl.edu/~rfield/PHY2061/images/relativity_13.pdf

    Yes, as per the above link, with the same scenario (two obsevers in relative motion at the same point measure how the E-field transforms).
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