# Re: toroid shaped coil capacitance

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Sent: 	Saturday, January 03, 1998 1:33 PM
To: 	Tesla List
Subject: 	Re: toroid shaped coil capacitance

Tesla List wrote:
>
> From:   D.C. Cox[SMTP:DR.RESONANCE-at-next-wave-dot-net]
> Sent:   Friday, January 02, 1998 6:37 PM
> To:     Tesla List
> Subject:        Re: toroid shaped coil capacitance
>
> to: Mark
>
> Do your reference books contain any equations for the "suface area" of both
> a sphere and torus?  I'm working on an article for the TCBA and have the
> equations for capacitance but not surface area.  Thanks in advance.
>
> DR.RESONANCE-at-next-wave-dot-net

TO: DR. RESONANCE

I use the equations from the " MACHINERY'S HANDBOOK 17TH ED"
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for a sphere   area (sq/in)= pi x dia^2

for a 5" sphere
3.1416 x 5"^2
3.1416 x 25
78.54 sq/in surface area
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for a torus I will try to discribe as follows:

if my torus (15" major O.D.) is made out of (5" minor O.D.)
dryer duct I would have a 5" empty space in the middle.
now the AVG.DIA.(a circle formed by a line following the center
of the dryer duct) of this torus would be 10".

so: area (sq/in)= pi^2 x avg.dia x minor dia.

3.1416^2 x 10" x 5"
9.8696 x 50"
493.48 sq/in surface area
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Hope this helps :>)

Rick L. Kirby

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