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Re: interesting secondary phenomonea



Original poster: "Antonio Carlos M. de Queiroz" <acmdq@xxxxxxxxxx>

Tesla list wrote:
Original poster: Shaun Epp <scepp@xxxxxxx>


----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Wednesday, January 31, 2007 10:47 PM
Subject: Re: interesting secondary phenomonea


Original poster: "Antonio Carlos M. de Queiroz" <acmdq@xxxxxxxxxx>

Air or vacuum capacitors store energy as any other capacitor, in the field between the oppositely charged plates. The presence of a dielectric is equivalent to interpose a lot of small insulated conductors between the plates, forming a network of capacitors between the plates that has the effect of increasing the capacitance between the terminals. That story about capacitors storing charge at the surface of the dielectric and not at the plates is a natural consequence of the presence of the dielectric in contact with the plates. The charges simply move, by creeping or sparking, to where they are attracted by the electric field. If a capacitor is charged at low voltage and the plates are quickly moved
away from the dielectric, most of the charge remains in the plates.

Antonio Carlos M. de Queiroz

I guess that is why variable capacitors work!

If the charge remains on the plates when the dielectric is removed, then why does the dielectric matter? I know it does matter but your explanation seems to counter that.
The dielectric serves as a convenient way to keep the plates separated, increases the breakdown voltage between the plates, and increases the capacitance for a given plate separation. The last effect happens just because the molecules are somewhat distorted by the electric field, what is equivalent to say that they are tiny insulated conductors, as I said above.

Antonio Carlos M. de Queiroz