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Capacitor and dielectric material

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shanmei

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The higher permittivity of the dielectric material inside the capacitor leads to a higher capacitance.

The left figure, the dielectric between the capacitance is the vacuum, the capacitance is low.

The middle figure, with silicon dioxide, a higher permittivity makes a higher capacitance than the left figure.

However, the right figure, if the dielectric material is a metal, like copper, the permittivity is huge, why it does not cause a high capacitance?

Assume that copper is not connected to the top and bottom metal layer of the capacitor.

Thanks.


permittivity.png
 

Re: capacitor and dielectric material

A capacitance of the third capacitor is equal to series connection of two capacitors formed by the gaps between the Cu slab and the plates.
The thickness of the Cu plate does not contribute to the capacitance.
 
Re: capacitor and dielectric material

I'm not sure what you intend with discussing the copper plate as dielectric. Its permittivity is almost purely imaginary, respectively it's not actually suited to make a capacitor. The permittivity parameter can be nevertheless useful to derive certain physical effects.
 
Re: capacitor and dielectric material

That makes senses that they behave as two capacitors connected in series when one metal is placed in the middle of the capacitor.

Could I draw the conclusion that the real permittivity serves as the dielectric material and the imaginal permittivity functions as the metal? Thanks.
 

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