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Feb17-13, 07:45 AM
P: 10
Quote Quote by DrZoidberg View Post
If the sphere of a VDG was made of activated carbon I'm pretty sure it would have the same capacitance as a polished sphere made of metal.
You could just write a program that simulates the behavior of electrons in metal. Just a very simple simulation that works basically like a game where every object is moved a little bit in each iteration of the game loop. Such a simulation would only need Coulomb's law to calculate the forces between the electrons and it would allow the electrons to move within arbitrarily shaped boundaries which represent the surface of the metal. Just put e.g. 1000 electrons into the simulation and let it run.
Ironically, this is EXACTLY the scenario that I was wondering about - it was the inspiration for my post. So you've hit the nail right on the head. My suspicions are the same as yours, that even though the activated carbon has a surface area orders of magnitude larger than the polished metal sphere, that somehow only the "externally directly visible" parts of the carbon matter, and the surface area by that measure is identical to the polished sphere, and they will have the same capacitance. But this is just intuition, and I'm not even sure if its right. Hence, my post ...

I'm not certain how to simulate it, but having also had decades of experience as a programmer, I think its easier to say it than to do :)