Re: Sphere/Toroid Comparison Chart

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

Original poster: "Kurt Schraner by way of Terry Fritz <twftesla-at-uswest-dot-net>" <k.schraner-at-datacomm.ch>

Sorry, there is an omission in the sphere eqation: it should read:

C =  epsilon x 25.4 x 0.5 x d / 9

of course the constants could be combined, so that

C[pF] =  epsilon x 1.41111 x d[inch]

...and the air dielectric constant should read 1.006 instead of 1.0006.



Tesla list wrote:
> 
> Original poster: "Kurt Schraner by way of Terry Fritz
<twftesla-at-uswest-dot-net>" <k.schraner-at-datacomm.ch>
> 
> John, Matt, Luc -
> 
> the equations, used to equate the respective capacitances of toroids vs.
> spheres, must have been:
> 
> The well known Bert Pool's eqn. for toroids:
> C = [1 + (0.2781-d2/d1)] x 2.8 x { pi x [(d1-d2) x (d2/2)] / 2 }
> 
> And for spheres:
> C =  epsilon x 25.4 x d / 9
> 
> with relative dielectric constant epsilon for air set to 1.0 (instead of
> 1.0006).
> 
> d1  sphere diameter in [inch]
> d2  sphere diameter in [inch]
> d   sphere diameter in [inch]
> C   capacitance in [pF]
> 
> This compares to about 3 decimal fractions in C.
> 
> Kurt Schraner