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Dimensions of Larmor formula

  1. Nov 21, 2008 #1
    The Larmor formula is:

    [tex]P=\frac{\mu_0 q^2 a^2}{6\pi c}[/tex]

    When I checked the units of this, I got [kg m^2 s^-1]. If it is in watts, shouldn't it be [kg m^2 s^-3]? I was pretty thorough in putting everything in SI units.

    [tex]\mu_0[/tex] is N/A^2 or kg m s^-2 A^-2.
    [tex]q^2[/tex] is C^2 or A^2 s^2
    [tex]a^2[/tex] is m^2 s^-2
    c is m s^-1

    Have I made a stupid error, or is this just the wrong way of doing the dimensional analysis?

    This is not homework.
     
  2. jcsd
  3. Nov 21, 2008 #2
    I don't think the formula is right.

    edit: Never mind. :P
     
    Last edited: Nov 21, 2008
  4. Nov 21, 2008 #3

    gabbagabbahey

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    The units of acceleration are [itex]m/s^2[/itex] not [itex]m/s[/itex], so the units of [itex]a^2[/itex] are [/itex]m^2/s^4[/itex] not [/itex]m^2/s^2[/itex].
     
  5. Nov 21, 2008 #4
    Stupid error it is then, thanks :P. You'd think after 4 years of uni I might be able to get that one right...
     
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