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See letter by Bruce Morgan in TPT Nov 1986- he talks about the dissectible capacitor and gives a reference to AJP article by J. Zeleny, "Observations and Experiments on Condensers with Removable Coats." vol 12 p 329 published in 1944- I don't have issues that far back, but if someone does, it might be useful to look at.
Bob Morse, St. Albans School, Washington, DC
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From: Carl E. Mungan
Reply To: phys-l@lists.nau.edu: Forum for Physics Educators
Sent: Wednesday, May 31, 2000 12:32 PM
To: PHYS-L@lists.nau.edu
Subject: Re: dissectible capacitor
To those who have responded, please provide more details of the
charges on each surface. To make estimations easier, why don't we say
the cylindrical capacitor is instead a parallel plate capacitor of
area A and separation d. Let the dielectric constant of the glass be
K. Suppose the Wimshurst is run up to a potential difference of V.
Now please specify the charges located on:
(1) the facing inner surfaces of the two metal plates
(2) the outer surfaces of the two metal plates
(3) the effective surface charge on the two sides of the glass sheet
under the following conditions:
(A) capacitor charged up and assembled
(B) capacitor isolated and disassembled
(C) same as (B) but after momentarily shorting the two metal plates together
(D) the reassembled capacitor
Obviously no net charge remains on the metal plates under condition
(C). Are you telling me that *net* charge reappears on them in step
(D)? If not, how can there be a potential difference between them?
Does *net* charge (not induced charge separation) migrate from the
metal to the glass and back during the above operations?
--
Dr. Carl E. Mungan, Assistant Prof. of Physics http://uwf.edu/cmungan/
Univ. of West Florida, Pensacola, FL 32514 850-474-2645 cmungan@uwf.edu
moving this fall to: US Naval Academy, Annapolis, MD 21402 410-293-6650