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Re: VDG sphere (fwd)



Bill asked:
Am wondering what kind of voltage i can get from a 16" or 20" sphere ?

Just off the sphere's surface E=Q/(4Pi epsilon R^2).
The potential of the sphere (rel to infinity) is V=Q/(4Pi epsilon R).
Combining: V=E*R relates the sphere potential to the "surface field" and the
radius.

For a given R, V is limited by E, which in turn is limited by corona
discharge into the air. This maximum E value depends on atmospheric
conditions, but as an example:

using E = 500,000 Volts per meter (a crude guess), and R = 0.5 meter gives

V= 0.25kV.

Bob

Bob Sciamanda (W3NLV)
Physics, Edinboro Univ of PA (em)
trebor@velocity.net
www.velocity.net/~trebor