What does it mean for this thing that is floating in space to be charged to 10kV? 10kV relative to what? You can't talk about voltages while saying to forget about the electric fields because, by definition, a voltage is the consequence of the spatial distribution of electric fields. Or, one could argue that it is the reverse, but in either case they are matched concepts and you can't have one without dealing with the other.

 

Charge in the case is a function of surface area on the outside. The inside matters not a whit.

Don't fall so in love with a theory that you ignore the many inputs, myself included, have told you.

Charge is not like water, it is static electricity, and rides on the surface of materials.

 

I am not ignoring I am simply going beyond conventional to the unknown. Yes, surface area matters. That's why I proposed a weir vs. a solid object. Charged to 10KV relative to any other object with less charge to which our single-plate/weir capacitor can be discharged to, via a wire. In this case I give almost not a whit to dielectric fields or surface area of opposite plates. I realize this isn't how most capacitors are made but the conditions certainly occur in nature (again I use the cloud analogy.) A single plate capacitor of large surface area can be charged and then discharged through a load, so long as the load has a continuous sink. Thank you for helping me articulate something not commonly found in textbooks, there is life after college.

 

Here is a Christmas message.

Bah Humbug.

 

I am not ignoring I am simply going beyond conventional to the unknown. Yes, surface area matters. That's why I proposed a weir vs. a solid object. Charged to 10KV relative to any other object with less charge to which our single-plate/weir capacitor can be discharged to, via a wire. In this case I give almost not a whit to dielectric fields or surface area of opposite plates. I realize this isn't how most capacitors are made but the conditions certainly occur in nature (again I use the cloud analogy.) A single plate capacitor of large surface area can be charged and then discharged through a load, so long as the load has a continuous sink. Thank you for helping me articulate something not commonly found in textbooks, there is life after college.

Since you aren't interested in listening to the reasons you have been given for why your reasoning is faulty, then by all means make your single-plate/weir capacitor and demonstrate how it has considerably more capacitance than a similar capacitor that uses a solid surface and then go prepare your Nobel acceptance speech -- and we will all happily applaud you and your contributions when you succeed.

 

I am not ignoring I am simply going beyond conventional to the unknown. Yes, surface area matters. That's why I proposed a weir vs. a solid object. Charged to 10KV relative to any other object with less charge to which our single-plate/weir capacitor can be discharged to, via a wire. In this case I give almost not a whit to dielectric fields or surface area of opposite plates. I realize this isn't how most capacitors are made but the conditions certainly occur in nature (again I use the cloud analogy.) A single plate capacitor of large surface area can be charged and then discharged through a load, so long as the load has a continuous sink. Thank you for helping me articulate something not commonly found in textbooks, there is life after college.

I think you are ignoring the difference between capacity and the capacitance field energy storage value. There is a real difference between the concepts! You need to look at the circuit path geometry when a current goes flows through it. A poor resistor analogy would be like an old carbon block rheostat, the resistance and power dissipation values depend on the connection points even if the rheostat as a whole has a set resistance and power dissipation capacity.

 

Wbahn: What is the surface area of a cloud? What is the total charge it is capable of holding? Why don't you listen to reasons why your conventional understanding is incomplete or inadequate?

 

http://coub.com/view/qzxv

 

You went from asking a question to making an assertion. Fact is, most of us here understand the theory deeply enough we know what will happen, but by all means, experiment, and document the experiment.

We often get people "thinking outside the box". If it violates well established physics then it is likely not going to work.

BTW, Science is making a hypothesis, then experiment to prove or disprove said hypothesis. What you have done is not science. I have made caps from scratch when I was in high school over 40 years ago, just to see how they worked. Used them too, in a crystal radio. How many have you made?

 

germeten, you've proposed a perfectly reasonable question. I happen to agree with most others that your answer to the original question is not correct, but physics isn't a popularity or rhetoric contest, physics is about how things actually work.

Would you be willing to test your idea? Or if someone else could demonstrate a test of whether adding crumpled surface area did or did not increase the capacitance of a pair of hemispheres, would that convince you?

 

Wbahn: What is the surface area of a cloud? What is the total charge it is capable of holding? Why don't you listen to reasons why your conventional understanding is incomplete or inadequate?

The question of the surface area of a cloud is irrelevant to the question you asked regarding the effect of increasing the small-scale surface area of the plates of a capacitor on the capacitance of that capacitor. The answer has been explained numerous times in numerous ways. The key element centers on the constraints imposed by the interaction of the electric fields and the surface, most notably that there can be no tangential component of the electric field at the surface of a statically charged conductor. You acknowledge that you don't understand the concept of an electric field being normal to the surface, yet ask why others won't listen to reason about their understanding being incomplete or inadequate? Interesting.

 

germeten, you've proposed a perfectly reasonable question. I happen to agree with most others that your answer to the original question is not correct, but physics isn't a popularity or rhetoric contest, physics is about how things actually work.

Would you be willing to test your idea? Or if someone else could demonstrate a test of whether adding crumpled surface area did or did not increase the capacitance of a pair of hemispheres, would that convince you?

I started with a question not fully formulated and is why my models changed during the discussion, not out of dishonesty and certainly not to be popular. I don't disagree that capacitance is a property of surface area, but in "non-normal" capacitors, that can be difficult to quantify, or where the opposite "plate" is. For example, in clouds, there is often internal arcing between thunderheads as well as to ground. Where is the charge being stored and what is the cloud's storage capacity? (Is there a tangential component? Omni-directional I would wager.) Another example is bins full of grain dust or conveyance pipes that are known to explode on occasion in presence of a spark or flame. The charge is created and held between the particles, often silaceous (tribo-electric) media, similar to a Van de Graf generator (his first patent incorporated charge conveyance tubes, not belts.) Granted this is a non-normal capacitor, an opposite plate to store a dielectric field isn't needed, just a discharge path to lower potential, to extract usable current. As far as I'm concerned these natural examples don't need further testing to prove concept but would be helpful toward building useful devices.

Of course a cap stuffed with foil might not be the best way for increasing surface area, that's why I proposed a porous sponge or weir, where inner surfaces can hold charge as well as outer. (Surface area is the basis for increased capacitance in super-capacitors.) The cap could be charged by any number of sources and be made of materials that would facilitate natural charging.

A weir could also serve as a useful pick-off medium (more surface area than just a comb) in a larger machine exploiting self-charging (moving) dust.

Charge can be held across the entire surface of an object, it doesn't require an opposite plate to create a dielectric field, that's just a convenience we learned to exploit in man-made capacitors.

 

Of course a cap stuffed with foil might not be the best way for increasing surface area, that's why I proposed a porous sponge or weir, where inner surfaces can hold charge as well as outer. (Surface area is the basis for increased capacitance in super-capacitors.) The cap could be charged by any number of sources and be made of materials that would facilitate natural charging.

Super-capacitors are electrochemical and depend on an electric double layer to operate. Electrons in the metallic electrode and ions in the electrolyte for charge separation on the layers in very close contact throughout the device. Just increasing the surface area with a sponge like structure without a way to make effective use of it by making close and direct paths for the field energy to be stored just won't work.
http://en.wikipedia.org/wiki/Electric_double-layer_capacitor

 

Hi,

I think the crux of the question is how the capacitance of a construction changes when the surface area increases while the distance at one edge increases in a manner that holds the width constant.

To illustrate this in a somewhat simple way, we can imagine that to start with we have two circular flat plates on top of each other with a thin separator sheet like paper or better yet just a thin layer of air. We also have two wires connected at the very center of each plate and this forms a capacitor. The capacitance is:
C=K*A/d
where
K is a constant,
A is surface area, and
d is the distance between the two plates.

Next, instead of using regular metal plates we use two plates made from a metal that stretches uniformly when the wires at the center are pulled away from each other, thus forming two right circular cones. As we pull on the wires, the distance between centers increases drastically while the circular edges stay in close proximity as before.

With this new construction if we consider the 'best case' where the capacitance depends only on the surface area and not the orientation of that surface area, then we have a new formula:
C=2*K*(pi*R*sqrt(R^2+D^2))/D
where
D is the separation distance at the center, and
R is the radius of the circular stretchable plates which now form the base of the two cones.

In this formula both K and R are constants with D the variable, and has derivative:
dC/dD=-2*pi*K*R^3/(D^2*sqrt(R^2+D^2))

Since D starts out positive and increases, and all the constants are positive except for one (the -2), this derivative is always negative which indicates that the capacitance always goes down.

So even though we are increasing the area the distance is causing a decrease in capacitance faster than the area is increasing the capacitance, and so the capacitance goes down. This is best case because we consider the area of the sides of the cone to contribute completely to the capacitance in the same way it does in a parallel plate capacitor when really it would contribute less. But if we prove that the best case doesnt work, then the less than best case cant work either.

Another possible construction would be with intertwined corrugated layers. These two layers would increase the capacitance because there we have the area increase but the distance does not increase. This could not be done with a randomly generated surface however like a crumpled piece of aluminum, but would have to be explicitly formed that way.

 

I've read that Eric Dollard claims to have removed the oil from one oil capacitor then dumped it into another oil capacitor and it had a charge already present. But that is what I read not witnessed. Which if true may suggest the dielectric does more of the heavy lifting than the plates.

 

And here I thought this thread had died a peaceful and merciful death....

 

And here I thought this thread had died a peaceful and merciful death....

Sorry

 

@Dimplewidget
You are allowed to start your own threads.
Getting the focus entirely on your question will get you specific, relevant answers.