I seem to remember some units convention that minimized the number of times
you had to write the permittivity of free space in long derivations.
Gauss's law went from the normal
>> div E = rho / epsilon-zero
to
>> div E = 4*pi*rho
I think it's only intent was to simplify long mathematical derivations in
theoretical work. You appreciate that when your homework involves a 2m long
equation for the quadrapole field of a rotating charged cube in the
radiation far zone! <g>
I can't seem to find now, but the classic grad text J. L. Jackson discusses
this. I do know the term "inch" never entered the discussion.
Nat
>In tooling around looking for something, I came across a couple of
>homework sets from the Princeton Physics Department that have students
>calculate problems in electrostatic units (esu)! How archaic! I don't
>have time to pursue this just now, but perhaps someone here (Gene? Joe?)
>would care to take this on. A citation you can start with is
> http://phy106.princeton.edu/hwk_s01/hw03sol.pdf
>This solutions page is copyrighted in 2001 by Edward J. Groth and David
>J. Nice.
>
>If nobody posts an inquiry this afternoon, I'll do so tonight after my
>afternoon class.
Sorry, I would not attempt it. All I remember about electrostatic units is
that the speed of light comes into the conversion to electromagnetic (emu)
and SI electric units.
Joe
Joseph B. Reid
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Toronto M5P 1C8 Tel. 416 486-6071
