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Homework Help: Some questions on Special and Newtonian Relativity

  1. Aug 22, 2009 #1
    1. The problem statement, all variables and given/known data

    Question 1: Is Ohm's Law (V = IR) invariant under Galilean transformations?
    Question 2: Model the earth as an ellipsoid or a spheroid, and find the lowest order correction to the inverse square law at points inside and outside the earth's surface.

    2. Relevant equations


    3. The attempt at a solution

    Question 1: Using the low velocity regime of the Lorentz transformations, we see that j = j', E = E' and so

    [tex]j = \sigma E[/itex]

    is invariant in both reference frames. As lengths are invariant under a Galilean transformation, this is equivalent to V = IR in all inertial frames. Is this correct?

    Can this be argued without using the Lorentz transformations, i.e. without treating Galilean transformations as a special case of the Lorentz transformation for [itex]v << c[/itex]?

    (Also, can resistivity or conductivity be regarded as a Lorentz invariant scalar?)

    Question 2: This has me stumped right now....I don't understand what has to be done here. I would appreciate if someone could point me in the right direction.
  2. jcsd
  3. Aug 23, 2009 #2
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