Re: Charge distribution on a Toroid (was spheres vs toroids)

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Antonio Carlos M. de Queiroz" <acmq-at-compuland-dot-com.br> 

Tesla list wrote:

 > Original poster: "Gerry Reynolds" <gerryreynolds-at-earthlink-dot-net>

 > Can you explain the cross section geometry of the infinitely thin rings?
 > Are they just filimentry.  Also, what about tapes and the orientation
 > relative to the surface of a toroid (or sphere)?

The rings are filamentary, except when I have to calculate their
potential
coefficients (vi = pii qi). I have then to assume a small radius for the
filaments. What gives best results appears to be to consider rings that
have the same surface area of the belt segments that they represent.
This
ends as a radius identical to the separation between the centers of
adjacent rings divided by 2Pi.
See: http://www.coe.ufrj.br/~acmq/tesla/capcalc.pdf (updated today)

I remembered another text with several capacitance formulas:
The American Instute of Physics Handbook.
Has the toroid formula, explaining how to evaluate it (as I did) and a
few others. it appears that all the known exact formulas, except for
that for the toroid (an maybe a recent one for a cylinder) were already
in Maxwell's 1873 book.

Antonio Carlos M. de Queiroz