Electric charge on conductors , capacitors

[Crazymechanic]

Hi I'm wondering why does the charge resides on the plates on a capacitor when it's charged but not on say two closely placed wires or circuit traces etc, well I do understand that charges stay on capacitor plates because the opposite charges tend to attract and with a distance between them they stay as close as possible for as long as possible.

So the question is more like , given the same amount of voltage does the charge accumulation depends on the conductor geometry or spacing between them ?
Say I have a parallel plate capacitor and two wires with the surface area the same as that of the plates , and the gap between each of the wires just as big as that of the plates will they ahve the same capacitance or no?



P.S. although I think it's impossible but would it be possible to make a capacitor which looses it's charge right after the source or the supply is taken away , well it wouldn't be a capacitor anymore but still , say I needed a device with which I can use + charge to attract some negative charge on the other plate but let it go just as when I disconnect the positive charge ?
As upon disconnecting a capacitor it would discharge slowly.

 

[davenn]

Hi I'm wondering why does the charge resides on the plates on a capacitor when it's charged but not on say two closely placed wires or circuit traces etc, well I do understand that charges stay on capacitor plates because the opposite charges tend to attract and with a distance between them they stay as close as possible for as long as possible.

the 2 "parallel wires of a circuit will have a charge on the for as long as there's a voltage applied
Remove the voltage and the charge will dissipate out into the attached circuitry

P.S. although I think it's impossible but would it be possible to make a capacitor which looses it's charge right after the source or the supply is taken away , well it wouldn't be a capacitor anymore but still , say I needed a device with which I can use + charge to attract some negative charge on the other plate but let it go just as when I disconnect the positive charge ?
As upon disconnecting a capacitor it would discharge slowly.

yes of course it is possible ... you just make a capacitor that has a very leaky dielectric between the plates so that current (charge) flows between the plates and balances out.
This of course would be a VERY poor capacitor

Dave

 

[dauto]

Hi I'm wondering why does the charge resides on the plates on a capacitor when it's charged but not on say two closely placed wires or circuit traces etc, well I do understand that charges stay on capacitor plates because the opposite charges tend to attract and with a distance between them they stay as close as possible for as long as possible.

So the question is more like , given the same amount of voltage does the charge accumulation depends on the conductor geometry or spacing between them ?
Say I have a parallel plate capacitor and two wires with the surface area the same as that of the plates , and the gap between each of the wires just as big as that of the plates will they ahve the same capacitance or no?

Two wires laying next to each other will have a small but non-vanishing capacitance that indeed depends on the exact geometry of the wires such as their sizes and distances. That means that small but non-vanishing charges might indeed build up in those wires. For most purposes these charges can be considered negligible (but not always). Excellent question.

 

[Crazymechanic]

@davenn , well yes a poor capacitor would do , but the problem is I need a good isolation between the plate so no current (in theory) runs between them but so that when I switch the negative potential off of one of the plates the + doesn't linger on the other as it would normally do.
The purpose is so that I could switch a negative potential on the legs of two capacitors in series so that i could get charges to run back and forth between them.
The thing is with a normal capacitor I can't do that just because the cap needs to be discharged or drained to ground for it to reverse polarity.

@dauto , why would that be an excellent question , just asking ? :)

 

[sardar]

I can explain the concept of electric charge on conductors and capacitors.

Electric charge is a fundamental property of matter and it can be either positive or negative. When a conductor or a capacitor is charged, it means that there is an excess of one type of charge (either positive or negative) on its surface. This charge can be created by transferring electrons from one material to another, or by inducing charges through the application of an external electric field.

In a capacitor, the charges reside on the plates because of the attraction between opposite charges. The plates are separated by an insulating material, which prevents the charges from neutralizing each other. The amount of charge that can be stored on the plates depends on the voltage applied and the capacitance of the capacitor. The capacitance is determined by the geometry and spacing of the plates. So, to answer your question, yes, the charge accumulation on a capacitor does depend on the conductor geometry and spacing between them.

In the case of two closely placed wires or circuit traces, the charges do not reside on the surface because there is no insulating material to prevent them from neutralizing each other. The charges will simply flow through the wires and neutralize each other. This is why capacitors are specifically designed to store charges, while wires are used for conducting current.

As for your question about creating a capacitor that loses its charge immediately after the source is disconnected, it is not possible. A capacitor works by storing charges on its plates, and these charges will remain there until they are discharged. If the source is disconnected, the charges will still remain on the plates and will slowly discharge over time. This is due to the inherent properties of a capacitor and cannot be changed.

In summary, the charge accumulation on conductors and capacitors depends on the geometry and spacing, and a capacitor cannot be designed to immediately lose its charge upon disconnection.