Static electricity, it's all capacitance?

Thread Starter

AngryGecko

Joined Jul 7, 2017
44
Good to know that that is cleared up.
Now would you care to tell us what is cleared up?
That you can see different charges in relation to each other as "capacitors" connected together. Analysing how they would charge/discharge the same way you would analyse a circuit with those "capacitors", if one "capacitor" were to short out. As long as you dont move the objects closer/further away from each other (that would change the capacitance) and don't change the charge between them. Other factors might also play a role like the dielectric material in between the objects etc.
 
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MrAl

Joined Jun 17, 2014
7,849
Capacitance is NOT the ability to store charge. Capacitance is a reactance/response to electric field flux. It's a result, not a cause.

Capacitance is a measure of how much local electric field flux aligns, with an external electric field flux.

The energy stored and expended is not due to charge storage......it's due to field alignment. The dielectric controls the alignment.....not the amount of charge.

A charge is NOT a quantum wave function. It's a real physical entity/object with size, shape and area. That's why it can line up.

An atom is simply a series tuned charge circuit. That's all it is.

Capacitance......electric flux alignment. Inductance.....magnetic flux alignment.
Hello there,

As to your first statement, i would agree if there was no such thing as absolute capacitance, but there is and that is because of the limit on the speed of light.

But even looking more casually we see that:
Q=C*V

What does that tell you?
If we had zero capacitance (which we can only obtain with zero distance and/or zero surface area) then we would have no charge with a given voltage, but with some capacitance we can have a charge stored somewhere. It's really a charge separation, but we count it as simply charge being stored. Call it energy if you like.

If we have two plates separated by a distance we can calculate what is known as the self capacitance. We dont have any charge or energy there yet, but we know what it would do if there was some introduced.

So maybe you think there is no such thing as inductance either then just because we happen to be able to measure it in a certain way?
 

MrAl

Joined Jun 17, 2014
7,849
Sure, but that's another non-physical circuit invented to allow the calculation of a physics discovery that people tend to confuse as related to current electricity. As soon as we need to actually measure some electrical quality of the space around this mythical isolated single point charge we need to add a test charge, so it's no longer isolated. I also agree with @BR-549 for once, capacitors don't store charge, they store energy in an electric field.
Hi,

Things are only mythical if they can not be shown to be true.
Not sure what you are getting at entirely though here. If we can measure it, IN SOME WAY, then it must exist.

We often refer to caps storing charge and you know it:
Q=C*V

Yes we can say it stores energy so what. The discussion of capacitors only has to include energy if we choose to include that in the discussion:
W=(1/2)*C*V^2

I chose to take the viewpoint of how the capacitor acts relative to the charge not the energy. If you like then just replace the word "charge" with "energy" and then the cap has the propensity to store energy and that is the self capacitance.
 

Thread Starter

AngryGecko

Joined Jul 7, 2017
44
Here is what I mean represented visually:2017-11-07 22.36.56.png
There are 3 objects that all have a certain charge relative to each other. These objects are the nodes in this equivalent circuit. Now lets say the 2 objects on the top touch each other and therefor the capacitor on the top starts discharging (resistor connected across it).
 

nsaspook

Joined Aug 27, 2009
7,733
Hi,

Things are only mythical if they can not be shown to be true.
Not sure what you are getting at entirely though here. If we can measure it, IN SOME WAY, then it must exist.

We often refer to caps storing charge and you know it:
Q=C*V

Yes we can say it stores energy so what. The discussion of capacitors only has to include energy if we choose to include that in the discussion:
W=(1/2)*C*V^2

I chose to take the viewpoint of how the capacitor acts relative to the charge not the energy. If you like then just replace the word "charge" with "energy" and then the cap has the propensity to store energy and that is the self capacitance.
What's mythical is notion of a isolated single point charge, that doesn't happen in deepest space.

Storing charge. Yes, it know it and try not to do it.
http://www.physicsclassroom.com/cla...on-Misconceptions-Regarding-Electric-Circuits
Electric circuits are all about energy, not charge. The charge is simply the medium which moves the energy from location to location.
We use electronic charge in the meaning of energize not of shuffling existing parts because the device wither it's a capacitor or battery remains overall electrically neutral when it's charged. The departure from electrical neutrality over space generates enormous forces to re-balance charge so the energy storage doesn't come directly from the charges as potential or kinetic energy because typically that's small in electronic devices, it comes from the electrical energy stored in fields around the charges in current electricity.

The force of repulsion of two +1.00 Coulomb charges held 1.00 meter apart is 9 billion Newton. This is an incredibly large force that compares in magnitude to the weight of more than 2000 jetliners.
http://www.physicsclassroom.com/class/estatics/Lesson-3/Coulomb-s-Law
 
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KL7AJ

Joined Nov 4, 2008
2,226
It seems that way to me. Static electric = charge holding still. Not flowing. No conductance. No conductors. No conductors means no inductors. The only thing left is capacitance.
Ya know, this really brings up an innertresting point. Theoretically, the entire universe, as a whole, is electrically neutral. There are the same number of electrons as protons. This means if you rub a balloon, you are upsetting the entire balance of the universe. Which means you have to create a surplus POSITIVE charge somewhere else.
This is a very real problem they ran into in developing plasma engines. If you start blorping a bunch of electrons out the back of a spaceship, sooner or later the spaceship becomes positively charged, which makes it want to go back to the electron cloud you just created. So the only practical answer is to blorp NEUTRONS out the back end, so you can get the acceleration without the charge differential. The only problem is you can't accelerate a Neutron by electrical methods in the first place.

A conundrum on a sticky bun here.
 

MrAl

Joined Jun 17, 2014
7,849
What's mythical is notion of a isolated single point charge, that doesn't happen in deepest space.

Storing charge. Yes, it know it and try not to do it.
http://www.physicsclassroom.com/cla...on-Misconceptions-Regarding-Electric-Circuits


We use electronic charge in the meaning of energize not of shuffling existing parts because the device wither it's a capacitor or battery remains overall electrically neutral when it's charged. The departure from electrical neutrality over space generates enormous forces to re-balance charge so the energy storage doesn't come directly from the charges as potential or kinetic energy because typically that's small in electronic devices, it comes from the electrical energy stored in fields around the charges in current electricity.


http://www.physicsclassroom.com/class/estatics/Lesson-3/Coulomb-s-Law

Hi again,

Interesting points.

But do you think it matters that much if it is mythical or not? We can still talk about it right? So what difference does it make to you if it iis mythical or not? Would be interested to hear your take on this.

I had previous mentioned that we can actually measure some of this stuff by looking for extremes and then approximating them and seeing what happens. This works sometimes because in the limits we often talk about infinities even though we cant get to a distance that is actually infinitely far from some other ponit. In the case of a point charge, we may not be able to get infinitely far from it but we can get far enough so that it looks almost the same as an infinitely far off second point or points and this works because the effect drops off suddenly or quickly. So without actually reaching an infinitely far off point, we see the same effect. For example, when the field drops off as 1/r^2 we see a fast dropping field so when we get to some point far off we see very little change after that, so we dont really have to get to infinity to see the result. With mutual inductance we see that fall fast too after some point, so fast that it no longer affects the required accuracy of the experiment even though it will still change. For example, at 1000 meters we may see 1.234nH, and moving 1 more meter may only make a difference of 1uH so we may then see 1.233nH, but then as we move farther and farther way we eventually start to see only maybe 1pH difference, so we may end up with 1.345nH but that extra 1pH doesnt do anything, and as we go farther, we still get 1.345nH, and if we reach infinity via mathematics we still only get 1.345nH, so we can say that at some REAL distance we saw the same thing within the required accuracy. This makes things look more real because there is little change as we move toward the 'mythical' point.

Saying that the capacitor does store 'charge' may not be entirely correct, but it is a useful circuit analysis tool as i am sure you know and makes certain things simpler. It does keep the charges separated though and we note that as a difference in charge. i am not saying that you must look at it this way for every problem, but for some problems it will make it easier to view that way and this technique has been around before you and i were even born :)

Some interesting stuff coming up in this thread.
 

MrAl

Joined Jun 17, 2014
7,849
Here is what I mean represented visually:View attachment 138849
There are 3 objects that all have a certain charge relative to each other. These objects are the nodes in this equivalent circuit. Now lets say the 2 objects on the top touch each other and therefor the capacitor on the top starts discharging (resistor connected across it).
Hi,

Yes, that's right. Also, if the left cap and right cap do not have the same voltage then they will start to change too. They will seek an equilibrium point where they both have the same voltage. The amount of 'charge' in each cap will then depend on the end voltage and capacitance values.
Note some people do not feel comfortable calling it 'charge, so just think of it in terms of energy then. The energy will be changed in each cap.
 
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nsaspook

Joined Aug 27, 2009
7,733
Saying that the capacitor does store 'charge' may not be entirely correct, but it is a useful circuit analysis tool as i am sure you know and makes certain things simpler. It does keep the charges separated though and we note that as a difference in charge. i am not saying that you must look at it this way for every problem, but for some problems it will make it easier to view that way and this technique has been around before you and i were even born :)

Some interesting stuff coming up in this thread.
It's useful in the same way the electrical water analogy is useful. Sure it makes things simpler if you think resistors or other electronic components store charge.

If you say it holds 'A Charge or Charge up' in the energy sense of the word that's cool but usually the second thing a beginner thinks after hearing stores charge is electrons and I think we all know that usually leads downhill fast when thinking about electronics and circuits.
 
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#12

Joined Nov 30, 2010
18,210
Theoretically, the entire universe, as a whole, is electrically neutral.
I am far too ignorant to address this idea on the macro scale, but it is my understanding that our planet, Earth, is fairly slopping over with spare electrons. By spare electrons, I mean electrons which are not attached to atoms as a pair with a proton.

I think you are mistaken, but feel free to educate me. Nobody ever told me that our planet is swarming with unattached electrons, but I believe it is because if there were no "spare" electrons, energy would be required to break the electron-proton bonds in a copper wire, and that energy conversion, showing up as heat, is not apparent.

Please excuse me as I digress. Once upon a time, I speculated about removing all the spare electrons from our planet, or placing a volt meter between Earth and our moon. I have received no useful answers, probably because I was so ignorant my question did not make sense. I think I said, "all electrons" instead of, "all unpaired electrons". My question remains a question. An answer would require someone a lot more educated than I am.
 

nsaspook

Joined Aug 27, 2009
7,733
I am far too ignorant to address this idea on the macro scale, but it is my understanding that our planet, Earth, is fairly slopping over with spare electrons. By spare electrons, I mean electrons which are not attached to atoms as a pair with a proton.

I think you are mistaken, but feel free to educate me. Nobody ever told me that our planet is swarming with unattached electrons, but I believe it is because if there were no "spare" electrons, energy would be required to break the electron-proton bonds in a copper wire, and that energy conversion, showing up as heat, is not apparent.

Please excuse me as I digress. Once upon a time, I speculated about removing all the spare electrons from our planet, or placing a volt meter between Earth and our moon. I have received no useful answers, probably because I was so ignorant my question did not make sense. I think I said, "all electrons" instead of, "all unpaired electrons". My question remains a question. An answer would require someone a lot more educated than I am.
There are huge numbers of 'free electrons' in conductors but they are not spare in the sense that it takes 'work' to separate or move them in a non-random fashion like current in a wire or as ions. That 'work' could be from the sun or the initial formation of the solar system so it's very possible that a planet or moon sized object locally would have a net charge but there is actually no way to define the net charge of the (closed or spatially infinite) universe so effectively the net charge is zero.

"To weigh something one needs a platform on which to stand to do the weighing."
 

#12

Joined Nov 30, 2010
18,210
There are huge numbers of 'free electrons' in conductors but they are not spare in the sense that it takes 'work' to separate or move them in a non-random fashion like current in a wire or as ions.
Yes, energy is required to move electrons in an orderly manner, but I believe you just said that there are lots of electrons on Earth with no proton available to pair with. That is what you said, isn't it?
 

nsaspook

Joined Aug 27, 2009
7,733
Yes, energy is required to move electrons in an orderly manner, but I believe you just said that there are lots of electrons on Earth with no proton available to pair with. That is what you said, isn't it?
It's free like in an orgy. They pass easily from the influence of one atom to another in a sea of electrons and atoms but if you need to isolate a stream of individual electrons then you need a device like a vacuum tube with heaters to separate electrons from the atoms and voltage to accelerate them in a path.
 

#12

Joined Nov 30, 2010
18,210
It's free like in an orgy. They pass easily from the influence of one atom to another in a sea of electrons and atoms but if you need to isolate a stream of individual electrons then you need a device like a vacuum tube with heaters to separate electrons from the atoms and voltage to accelerate them in a path.
Would you just answer the question? Are there more electrons than protons on this planet?
 

#12

Joined Nov 30, 2010
18,210
And a follow up question: Are there protons wandering around, not attached to electrons, and thus not making a hydrogen atom?
 

nsaspook

Joined Aug 27, 2009
7,733
Would you just answer the question? Are there more electrons than protons on this planet?
Due to charge conservation it's likely that there are about the same number as a charge imbalance creates enormous forces seen as lightning in nature. Equality is relative but even 1% can matter a lot.

Richard Feynman once said that if two persons stood at arm's length from each other and each person had 1% more electrons than protons, the force of repulsion between them would be enough to lift a weight equal to that of the entire Earth.

http://www.feynmanlectures.caltech.edu/II_09.html
 

BR-549

Joined Sep 22, 2013
4,938
The electrons in solid matter, probably do 99% of the interaction with the environment. Some elements are so well tuned......it would take great power to separate an electron. But most elements can be coached to free an electron.

Some elements can naturally share electrons. They are lightweight and have little inertia......are at a high energy level already......the tuned bond is very weak.....they get out of the gate all the time. One would think that the higher the energy level.....the stronger the bond. But not for an electron. An electron hates and expels energy...the lower the energy level....the greater the bond. The electron's fields are anti parallel. The higher the energy is....the more jitter and unstable it becomes. It's like a loaded spring with it's ratchet ready to slip.

The greatest source or free isolated protons and free isolated electrons......is a star. These huge, highly accelerated streams are emitted by all stars. These particles are not effected by gravity. And in our system, they are accelerated beyond Neptune. They are still gaining velocity at Neptune. Quite possibly way beyond that.

Why do they stay separated? Why not combine and make dipoles(H1 gas)? Could the hypothetical spherical Oort cloud be a place of re-assembly?

Interesting stuff. How bout this. A negative and positive charge flow with space....at the poles. To maintain surface charge neutrality. We know that there is much more water in the interior of the earth, than in the oceans...much much more. That means ions. Could we have charge shells in the interior of the earth? Powering and varying our magnetic field perhaps? Maybe neutrality is maintained across the surface vertically....not horizontally.

The fundamental questions are always the best.

Edit: No free protons. If one is isolated due to decay or collision.......it wont be alone for long. It will easily steal an electron......then combine with something. A water molecule perhaps.
 

nsaspook

Joined Aug 27, 2009
7,733
I guess the complete absence of a yes or a no means you don't know.
It means you didn't understand my answer. Charge conservation The earth and solar system are dynamic, not static set pieces and it doesn't take much of an imbalance in charge at the level of a planet to see very high potential energy states created locally.
 
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