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Re: Electrostatic Questions
Q = C x E If I remember correctly. Once the capacitor is charged then the Q
becomes a constant
except for high voltage leakage effects. Suppose that the capacitor has a
water dielectric.
If the water (dielectric constant 80 for distilled) is replaced with air
(dielectric constant 1).
With the charges still on the metal plates the Q is still constant but C has
changed by a
factor of 80. Therefore E must increase by a factor of 80. Does anyone
have an electrostatic
voltmeter to try and measure if the voltage changes with different
dielectrics?
This can be related to Tesla coil operation. The humidity in the air
(dielectric constant 80)
would tend to slightly increase the capacitance of the secondary (tertiary)
tank circuit.
This would imply the need for greater power to the coil on humid days to
produce a
spark discharge of the same general length (f(E)). I have experienced this
with my coil operated in
a cold air conditioned room (2KW to produce 52" discharge-90 degrees, 90%
RH) and on a very hot humid day outside (2.4KW to produce 52" discharge-68
degrees, 30% RH).
Barry
----------
|From: "tesla-at-poodle.pupman-dot-com"-at-PMDF-at-PAXMB1
|To: Benson Barry; "Tesla-list-subscribers-at-poodle.pupman-dot-com"-at-PMDF-at-PAXMB1
|Subject: Re: Electrostatic Questions
|Date: Tuesday, August 27, 1996 1:20AM
|
|<<File Attachment: 00000000.TXT>>
|> Subject: Electrostatic Questions
|
|From hullr-at-whitlock-dot-comMon Aug 26 21:31:26 1996
|Date: Mon, 26 Aug 1996 12:22:08 -0700
|From: Richard Hull <hullr-at-whitlock-dot-com>
|To: tesla-at-pupman-dot-com
|Subject: Re: Electrostatic Questions
|
|Tesla List wrote:
|>
|> >From rwall-at-ix-dot-netcom-dot-comSat Aug 24 22:08:35 1996
|> Date: Sat, 24 Aug 1996 07:01:30 -0700
|> From: Richard Wayne Wall <rwall-at-ix-dot-netcom-dot-com>
|> To: tesla-at-pupman-dot-com
|> Subject: Electrostatic Questions
|>
|> 8/24/96
|>
|> I have a couple of questions regarding electrostatics.
|>
|> In the metal pail capacitor experiment where the cap is charged and the
|> pails are removed and grounded and then later replaced, it is obvious
|> that the charge resides on the dielectric rather than the metal plates.
|>
|> Question 1: If a gas (air) or liquid dielectric cap is charged and the
|> liquid is drained or the air is blown away from the plates what happens
|> to the charge on the cap?
|
|
|
|In air and a vacuum, it goes bye-bye! Charge is distributed over larger
|area. (it is never lost-conservation laws-) But, for us real people who
|put on the real charge, with real energy, it is REALLY- just gone!!!
|Liquids can be charged and transported, though. There are many mysteries
|involving the study of non-standard, non-bulk, dielectrics which are
|subtle. The answers to these questions are, often, just not known by
|many physicists if questioned in a situation where they can't research
|the matter! I have caught several off guard. There is just no money in
|trivia knowledge of old dead subjects like electrostatics and some
|physicists just dodge or avoid definitive answers (Good thing too as
|there are few definitive answers available for some phenoena!)
|This may sound bad for them, but these tenured icons of science are just
|like you and me only vastly more practised is narrow areas.
|> R.Hull
|
|
|
|> I am very interested in DC properties of TCs. I have devised various
|> schemes to add DC bias to the coil so that the TC discharge will also
|> exhibit a DC bias - sort of pulsating DC from the toroid.
|> Incredibible DC voltage and current may be developed with only a small
|> to moderate TC.
|>
|> One way to introduce this DC bias is with a main capacitor that
|> selectively charges during the AC waveform, ie., charges easier
|> positively or negatively or vise versa. Note this is not an
|> electrolytic or any other polarized cap. Since most caps are
|> essentially two metalic plates on either side of a dielectric,
|> selective charging would ordinarily be unusual.
|>
|> Question 2: Has anyone made a cap by placing the metal plates on an
|> electret dielectric? Seems to reason that an "electret cap" would
|> selectively charge/discharge. The big question is can ordinary
|> polymers such as polyethelene be made (converted) into an electret?
|> Richard H. or Kim G?
|
|I have only limited experience with electrets. They seem magical, but
|are really just special dielectrics with properties which let them
|continually facilitate charging. This is key to remember. The charging
|of plates from electrets still require some triboelectric action (input
|energy) and charge separation through motion! (separating the plate to
|be charged from the electret.) Electrets can be discharged forever
|without proper electrostatic shielding. Weak electrets require frequent
|recharging. The classic electret of bygone ages is a mix of Beeswax and
|Carnauba wax. Modern electrets include some forms of specially prepared
|teflon. Oleg Jefimenko and R.A. Ford have books which discuss electrets.
|Richard Hull, TCBOR
|
|
|>
|> RWW
|