capacitance equation for toroids

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

Original poster: "Dr. Resonance by way of Terry Fritz <teslalist-at-qwest-dot-net>" <resonance-at-jvlnet-dot-com>


Someone on the list recently inquired regarding the equation for a torus:

let D = major dia. measured to outer edge of toroid

let d = minor dia. measured across "inner tube"

then, for conditions in which the ratio of d/D is greater than 0.25,

Cpf = (0.94 *d) + (0.584 * d)

and for conditions in which the ratio of d/D is less than 0.25,

Cpf = 4.57 * (D-d) / ln (8 * (D-d) / d))


Another simple equation, although not as accurate (but close for most 
sizes) is:

Cpf = D + d / 2.56


For a sphere the equation is Cpf = 1.4 * dia.


Dr. Resonance

Resonance Research Corporation
E11870 Shadylane Rd.
Baraboo   WI   53913