Robin van Spaandonk wrote:
In reply to John Berry's message of Fri, 9 Feb 2007 08:12:00 +1300:
Hi,
[snip]
That's how many electrostatic machines work such as the Wimshurst.
There are 3 different things, voltage, field strength and charge imbalance,
in this case the Voltage goes up, however the field strength goes down
(though is still considerable and covers more area) and the charge imbalance
obviously remains the same.
It is also possible to increase the electric field density without changing
the voltage or net charge imbalance by use of a point.
[snip]
If the charge remains constant while the plates are being pulled apart, and the
capacitance if inversely proportional to the separation distance, then the
voltage should be proportional to the separation distance, and consequently the
field strength (Voltage / distance) should be constant.
It is, as long as the separation between the plates is much smaller than
the diameter of the plates.
Field near a point falls off as 1/r^2. Field near a wire falls off as
1/r. Field near a flat plat falls off as 1 (i.e., it doesn't fall off).
However it's afternoon, and I may I have goofed once again. :(
Regards,
Robin van Spaandonk
http://users.bigpond.net.au/rvanspaa/
Competition provides the motivation,
Cooperation provides the means.
