- #1
Omegatron
- 68
- 2
I'm an electrical engineer, so I'm used to circuits and components and know them pretty well. What I don't know is "broken circuits"; the physics of a charged object hanging out in space by itself, discharging into other objects, etc. So I'd like to ask a few things that have been confusing me lately:
1. This site talks about the voltage on a single charged sphere floating in space. But what is that voltage measured relative to? Isn't voltage by definition a "potential difference"? A difference between two points? (And what does "potential" mean, anyway?) So wouldn't this sphere's voltage have to be measured relative to another point? Is that "other point" infinity? If so, what does that mean exactly? We explored how to calculate stuff like this in electromagnetics class, but I guess I never really learned some of the concepts behind our calculations...
2. If I take a metal plate and hang it in the air by insulators, scuff my feet along the ground, and touch it, I can charge it. Now what if I put another metal plate very close to it with a dielectric between them? (A floating capacitor.) If I do the same thing, can I "fit" more charge on the plate that I touched, because the oppositely charged particles from the other plate crowd up next to it and "condense" more charge into a smaller area/volume? (Hence the word "condenser". (Does anyone know who invented the word "capacitor" and why it replaced condenser in English but not in any other language?))
3. If I charge up one side of a floating capacitor, as described above, can I connect the other plate of that capacitor to a neutral conductor and "extract" charge from it? (Because there should be a charge imbalance if I am thinking of this correctly.)
4. If I do the same thing again, but this time the other side of the cap is connected to a large conductor (like the Earth), can I fit even more charge than in the case of #2?
This is all related to an experiment I've been looking at, which I will start another thread for. :-)
1. This site talks about the voltage on a single charged sphere floating in space. But what is that voltage measured relative to? Isn't voltage by definition a "potential difference"? A difference between two points? (And what does "potential" mean, anyway?) So wouldn't this sphere's voltage have to be measured relative to another point? Is that "other point" infinity? If so, what does that mean exactly? We explored how to calculate stuff like this in electromagnetics class, but I guess I never really learned some of the concepts behind our calculations...
2. If I take a metal plate and hang it in the air by insulators, scuff my feet along the ground, and touch it, I can charge it. Now what if I put another metal plate very close to it with a dielectric between them? (A floating capacitor.) If I do the same thing, can I "fit" more charge on the plate that I touched, because the oppositely charged particles from the other plate crowd up next to it and "condense" more charge into a smaller area/volume? (Hence the word "condenser". (Does anyone know who invented the word "capacitor" and why it replaced condenser in English but not in any other language?))
3. If I charge up one side of a floating capacitor, as described above, can I connect the other plate of that capacitor to a neutral conductor and "extract" charge from it? (Because there should be a charge imbalance if I am thinking of this correctly.)
4. If I do the same thing again, but this time the other side of the cap is connected to a large conductor (like the Earth), can I fit even more charge than in the case of #2?
This is all related to an experiment I've been looking at, which I will start another thread for. :-)