smooth sphere vs unsmooth sphere
From: D.C. Cox [SMTP:DR.RESONANCE-at-next-wave-dot-net]
Sent: Friday, April 03, 1998 7:04 PM
To: Tesla List
Subject: Re: smooth sphere vs unsmooth sphere
to: Tristian, Bert, Sulaiman, et. al:
We used a rotating field mill electrostatic voltmeter to take measurements
of potential difference for some of our various different sizes of Van de
Graaff generators. Between two spheres of dis-similar size, ie, 18 inch
main to 9 inch (2:1 ratio) and other 2:1 ratio sizes we were obtaining
nearly consistent readings of 26.4 kV/cm which is in near agreement to the
3 kV/mm as mentioned. These were DC potentials.
> From: Sulaiman Abdullah [SMTP:sulabd-at-hotmail-dot-com]
> Sent: Friday, April 03, 1998 3:48 AM
> To: tesla-at-pupman-dot-com
> Subject: Re: smooth sphere vs unsmooth sphere
> >From: Bert Hickman [SMTP:bert.hickman-at-aquila-dot-com]
> >Sent: Friday, March 27, 1998 8:22 AM
> >To: Tesla List
> >Subject: Re: smooth sphere vs unsmooth sphere
> >Tesla List wrote:
> >> ----------
> >> From: Sulaiman Abdullah [SMTP:sulabd-at-hotmail-dot-com]
> >> Sent: Thursday, March 26, 1998 10:25 AM
> >> To: tesla-at-pupman-dot-com
> >> Subject: Re: smooth sphere vs unsmooth sphere
> >> Tristan,
> >> You can estimate the voltage produced by your coil now.
> >> VOLTAGE = 2.83 MV x R (R = radius in meters)
> >> I just worked this formula out today based on a commonly accepted
> >> of 25 micro-coulombs per square meter being the limit before
> >Where'd you find the 25 uC/square meter figure? Was this for DC?
> >-- Bert --
> Yes, this rersult is near enough to a similar 'rule of thumb' which
> gives 3 kV / mm whether in a 'gap' or at the edge of a sphere.
> V = 2.83 Mv x R (R = radius of sphere in meters) ... comments?