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Re: capacitance of a disk

I found the following at



FROM Michael Schoessow, TCBA NEWS Volume 6, #2, 1987, pp 12-15

C, uufd, OD = 6 12 18 24 30 36

DISK 5.3 10.7 16.0 21.3 26.7 32.0

SPHERE 8.4 16.8 25.1 33.5 41.9 50.3

I don't know if these are reliable. It isn't particularly
encouraging that Schoessow doesn't seem to be understand the
enormous economy of scaling laws. (Kind of reminiscent of stores
offering "1 for $.59, 2 for $1.18!") But then, we are clearly
talking about engineers here. (Sorry, brian ... and Dad.) I do
note, however, that he gets the sphere essentially right and his
claim is that the isolated disk has a capacitance that is 27% more
than half that of a sphere of the same radius. I had originally
guessed 10 to 20% and my calculations hinted at more like 40%.
All things considered, 27% seems plausible.

John Mallinckrodt
Cal Poly Pomona