Re: Capacitance of Archimedean coil

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

Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz <teslalist-at-qwest-dot-net>" <acmq-at-compuland-dot-com.br>

Tesla list wrote:
 >
 > Original poster: "Marko by way of Terry Fritz <teslalist-at-qwest-dot-net>" 
<moyson-at-tig-dot-com.au>

 > The Medhurst formula calculates a cylindrical coil capacitance. Does this
 > formula has come about purely from experimental means, or can it be derived?

The ideal calculation would be of the capacitance of a cylinder
with a sinusoidal voltage profile along it. Looks complicated.
The result is close to one half of the body capacitance of a cylinder.
The expression for this capacitance is known (but I can`t locate it
now).

 > I am looking to calculate the capacitance of a flat spiral coil.
 > I have not been able to find a formula for capacitance of other coil forms
 > like the flat spiral coil.
 > Does anyone know of this?
 > Or is there a method for deriving a coil capacitance??...my textbooks are
 > not helping...

Try one half of the body capacitance of a disk, that is:
Cdisk=4*pi*8.85e-12*diameter/pi, diameter in meters.

Antonio Carlos M. de Queiroz