every conductor has inherent capacitance

[PG1995]

Hi

A capacitor has capacitance due to different types of charge of its plates. Okay. This is understandable. A conductor is said to have uniform spread of charge and charges (i.e. electrons) can flow one place to another to neutralize an imbalance of charges. Still, it is said every conductor has an inherent capacitance. How is this possible? In case of a capacitor energy is invested to create an imbalance of charge; there is nothing 'natural' in this case. How can a conducting wire have any capacitance? Please help me with it. Thank you.

Regards
PG

 

[FvM]

Capacitance exists between conductors or between a conductor and ground. In any case, it depends on the conductor geometry. In so far, I don't see that inherent capacitance of a conductor is a plausible term.

 

[ark5230]

This point is explained in short in wikipedia under Self-capacitance at the following link

Capacitance - Wikipedia, the free encyclopedia

That makes it very clear that every conductor has certain capacity to store electric charge, just like capacity of a vessel to store liquid or water. Amount of water represents amount of charge, water level or height is related to electric potential. More the water it can hold with lesser increase in level / height, higher is the capacity of the tank. Same logic applies to capacity or capacitance of a conductor.

 

[FvM]

That makes it very clear that every conductor has certain capacity to store electric charge, just like capacity of a vessel to store liquid or water. Amount of water represents amount of charge, water level or height is related to electric potential. More the water it can hold with lesser increase in level / height, higher is the capacity of the tank. Same logic applies to capacity or capacitance of a conductor.

Unlike a tank, the conductor doesn't store the charge inside rather than in the external field. The self-capacitance is in fact the capacitance of a conductor against ground (respectively the enviroment) when the distance extends to infinity.

 

[PG1995]

Thanks a lot, FvM.

Okay. Now I understand that capacitance can exist between a conductor and some nearby object such as wire or ground. But still to have some capacitance one of the 'plates' should have uneven spread of the charge so that it can disturb the charge distribution in a nearby object. Say, the conducting wire has an evenly spread charge throughout it, then how can it affect anything nearby to develop capacitance when it is a neutral conducting material.

I have also read that capacitance can exist between different sections of a same wire. For example, please have a look on the linked scan: https://img11.imageshack.us/img11/8789/inductrcapacitance.jpg

Please keep your explanation simple and don't make things more complicated. Thanks a lot.

Regards
PG

 

[alexxx]

I have also read that capacitance can exist between different sections of a same wire. For example, please have a look on the linked scan: **broken link removed**

Please keep your explanation simple and don't make things more complicated. Thanks a lot.

For example, an inductor often acts as though it includes a parallel capacitor, because of its closely spaced windings. When a potential difference exists across the coil, wires lying adjacent to each other at different potentials are affected by each other's electric field. They act like the plates of a capacitor, and store charge. Any change in the voltage across the coil requires extra current to charge and discharge these small 'capacitors'. When the voltage changes only slowly, as in low-frequency circuits, the extra current is usually negligible, but when the voltage changes quickly the extra current is larger and can be significant.

Parasitic capacitance - Wikipedia, the free encyclopedia

Simple enough!

 

[ark5230]

Charge can be evenly distributed on spherical conductors. For the rest of the conductors it can not, this is due to shape of the conductor, charge has tendency to migrate at sharp edges and tips. Capacitance is simply the ability to store charge (capacity).