Re: Spheres vs Toroids

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

Original poster: "Antonio Carlos M. de Queiroz" <acmq-at-compuland-dot-com.br> 

Tesla list wrote:
 >
 > Original poster: Paul Nicholson <paul-at-abelian.demon.co.uk>

 > A better value is 40.583978.  Yours is slightly in error
 > because you haven't used enough decimal places for epsilon.
 >
 > Multiply your answer by 8.854188/8.85 to get the correct value.

Verifying:
 >From the relation between the speed of light and the
constants u0 and e0:
c=1/sqrt(u0*e0)
e0=1/(u0*c^2)
u0 is defined as 4*PI*1e-7.
A precise measurement of c is 2.997924e8 m/s.
So, e0=8.854191e-12.
But the toroid is in air, not vacuum. Would this cause the difference?
I have a book here that lists e0=8.85418e-12, +/-0.000002e-12.
Approximating the speed of light to 3e8 m/s leads to a nice number,
that may cause the impression that e0 is also a definition:
e0=1e-12/(36*PI)=8.841941e-12
I will adopt your number, e0=8.854188e-12.
With this, I get C=40.5839741468 pF for the 90x30 cm toroid in free
space.

Antonio Carlos M. de Queiroz