current returning to a different source

[crossman]

Just thought of this when I woke up....

First, you have to account for the other two power lines. The only reason I mention them is you show positive charges along the tower when they are almost entirely negated by the e-fields of the other two lines.

Take a point in the sine wave where A phase is at the negative peak. B phase and C phase will be at 1/2 the positive peak. Now draw a tower with A, B, and C in whatever arrangement you feel is representative of an actual powerline. Now consider the capacitance between these lines and observe the affect on the electrons in the tower.

B phase and C phase will attract electrons towards them, while A phase is repelling these same electrons. This will serve to INCREASE the positive charge on the tower in the vicinity of A phase. This is contrary to your statement that the electrostatic fields from the other phases negate any positive charges on the tower. No, they make the positive charge even stronger!

At the instant we are speaking of, the portions of the tower in the vicinity of B and C will be negatively charged. The portions of the tower in the vicinity of A will be positive. Obviously the polarities are changing with time, but at any given time the tower will have positive and negative charges at various places.

 

[ELA]

Oh, and for what its worth, the latest XKCD is right on target.
http://xkcd.com/386/

I've appreciated the discussion so far!

-Jon

Excellent!

But who is correct? :smile:
I hope you can get some sleep Crossman.

 

[crossman]

Thanks ELA. I did go to bed relatively early. But I woke up 30 minutes early with thoughts of this thread in my head.

 

[rattus]

Kiss

Kiss

All this nit-picking about the exact path of the field lines and the exact distribution of charge is simply clouding the issue. We know the caps exist, so now an equivalent circuit is in order. Crossman has provided that equivalent circuit.

To make things dog-simple, we may assume a single-phase line--one hot and one earthed return. Now we have three caps--hot to helicopter, return to helicopter, and helicopter to earth. The last two caps are in parallel, so we end up with two caps in series with the helicopter being the common plate as in Crossman's sketch.

It doesn't get much simpler than this!

If you criticize this argument without understanding, then shame on you!

If you are merely obfuscating, then shame on you twice!

If this argument is indeed wrong, then shame on me.

 

[crossman]

All this nit-picking about the exact path of the field lines and the exact distribution of charge is simply clouding the issue. We know the caps exist, so now an equivalent circuit is in order. Crossman has provided that equivalent circuit.

If you criticize this argument without understanding, then shame on you!

Thanks Rattus. I am going to tone it down a bit now in the defense of the argument. The phenomenon is clearcut to me. There can be no current flow without a complete path. And.... two isolated unequal charges in space is the very definition of "potential difference" and therefore is a source of voltage. A single conductor between these two charges is a completed circuit.

For everyone else, if you don't like the conclusion, then offer one of your own with substantiation.

 

[Rick Christopherson]

Thanks Rattus. I am going to tone it down a bit now in the defense of the argument. The phenomenon is clearcut to me. There can be no current flow without a complete path. And.... two isolated unequal charges in space is the very definition of "potential difference" and therefore is a source of voltage. A single conductor between these two charges is a completed circuit.

For everyone else, if you don't like the conclusion, then offer one of your own with substantiation.

This is all I have been trying to say since the very beginning. When did you flip-flop to agree with this?

 

[zog]

Welcome to the Forum Rick

 

[Rick Christopherson]

Welcome to the Forum Rick

25 pages of arguments, hostile responses, and snide comments about me being some sort of crackpot, and all of a sudden, we are right back to the original concept I stated in the beginning. :-? And you guys wondered why I wouldn't let it go?

I have enjoyed this discussion; It has been interesting; and no, I am not mad. :grin:

 

[zog]

I have been down the same path on other topics.

 

[crossman]

You're not going to get away with it Rick.

The following two quotes are yours:

any time you have a difference in voltage, you will have current flowing. It does not matter if there is a completed circuit or not.

There is nothing in Ohm's Law that says current has to return to the source before it can flow.

This quote is mine:

two isolated unequal charges in space is the very definition of "potential difference" and therefore is a source of voltage. A single conductor between these two charges is a completed circuit.

What you said is not the same thing as what I said.

 

[Rick Christopherson]

You're not going to get away with it Rick.

The following two quotes are yours:

any time you have a difference in voltage, you will have current flowing. It does not matter if there is a completed circuit or not

I already discussed this passage once before, and as I said then, it was assumed that a conductor existed. This was simply an error of omission, not of principle. It is comparable to a typo.

As for the second half, that is still correct. A circuit is defined as a ?Closed Path?, and I have never strayed from that definition throughout any posting I have ever made on this topic. A single wire between two circuit elements is defined as a ?Network?, but it is not a circuit until you close the path. (Engineering Circuit Analysis, Hayt and Kemmerly)

There is nothing in Ohm's Law that says current has to return to the source before it can flow.

This still stands, and your statement below is saying exactly the same thing. Ohm?s Law can be applied to a circuit, a network, or just a circuit element. Ohm's Law is not predicated on having a completed circuit.

two isolated unequal charges in space is the very definition of "potential difference" and therefore is a source of voltage. A single conductor between these two charges is a completed circuit.

What you said is not the same thing as what I said.

Oh quite to the contrary, your statement is exactly what I was saying from the very beginning, and is the same as I have been sticking with this entire time.

I did not correct you on your misuse of the term "circuit" in the above quote because I felt that would be as pedantic as correcting someone's spelling errors. I knew what you were saying regardless whether you correctly called it a network or a circuit. Maybe I should have. Nevertheless, what you described is exactly what I have been saying since the beginning.

Here is a copy of the second posting I made on this topic to clarify the first posting.

As I said in my original posting, I know that this will raise a few hackles, and it will be hard to swallow. That's because we automatically view current flow as requiring a circular loop. While not really feasible, just for example, if you connected a wire between the Earth and the Moon, you would have a monstrous current flowing in that wire, even though there was no return circuit. The reason is because of the innate voltage difference between these two bodies.

Remember this Earth to the Moon analogy that the whole forum summarily dismissed and mocked me for; well that is exactly the same situation you just described above.

 

[crossman]

Your failure is that you misunderstand the term "voltage source". Two isolated bodies with unequal charge is a single voltage source and a single circuit element. Therefore a conductor from one isolated body to the other is a complete circuit.

While doing circuit analysis, considering two isolated bodies with unequal charge to be two seperate circuit elements is the same thing as considering a battery with its positive terminal and negative terminal as being two seperate circuit elements.

Thank you for the lively discussion. My understanding has been solidified over the past 9 days.

 

[Rick Christopherson]

Two isolated bodies............ with unequal charge is a single voltage source and a single circuit element. Therefore a conductor from one isolated body to the other is a complete circuit.

Let me see if I am getting this straight....Two Isolated Bodies.....well they're not really isolated........and there really isn't two of them? Is that pretty much what you just wrote? :grin: :grin: :grin: :grin: :grin:

So explain to me this: If you have two isolated bodies with unequal charge, and you connect them with a wire (resistor), where is the return path that everyone has been saying must exist?

Quick...tell me it's a capacitor.

Oops, a capacitor is a passive element and current is going to flow in the same direction as the current through the resistor.

 

[crossman]

We have two isolated bodies with unequal charge. There is an electrostatic field between them which stores energy. These bodies influence one another across distance. There is an electric potential difference between the bodies. The bodies are a source of voltage.

If we connect a resistor between the two bodies, electrons will flow from the more negative body to the more positive body. From an elementary perspective, it may seem that the diagram below is not a complete circuit. There is no "loop". Doesn't a circuit have to be a loop?

A little redrawing will illustrate that this is indeed a complete circuit from one side of a voltage source to another. There is no difference between the drawing above and the drawing below. They are completed circuits.

The above drawing is a completed circuit with one voltage source and one resistor. On that note, so is the second drawing.

 

[crossman]

One more thing....:roll:

Rick, if you will go to page 25 of this thread and review the remark you made in Post #246, and then go to page 26 and review what you wrote in Post #253 and in your second paragraph of Post 251, you will find that you have directly contradicted yourself.

Edit: corrected post #s

 

[steve66]

Rattus:

Eddy currents result from alternating magnetic fields.

Exactly what you have within 10' of a transmission line.

They flow in closed paths in conductors such as Watt hour meter discs and transformer iron.

And the metal components of a helicopter.

I can't see any connection with this problem.

I'm only trying to explain why there is an arc from the transmission line to the helicopter.

I'm not sure why you and crossman are trying to explain it with capacitors.The visible arc shows the current flow is actually by conduction. You don't get an arc through a capacitor when a current flows through it.

Steve

 

[Rick Christopherson]

One more thing....:roll:

Rick, if you will go to page 25 of this thread and review the remark you made in Post #246, and then go to page 26 and review what you wrote in Post #253 and in your second paragraph of Post 251, you will find that you have directly contradicted yourself.

Edit: corrected post #s

HUH? :-? Where is the contradiction?

 

[crossman]

Steve: Eddy currents are formed insideof conductive bodies when exposed to a changing magnetic field. These eddy currents are not free to jump off the body. Certainly they exist in the helicopter when it is close to the powerline, but they circulate inside the helicopter components.

The helicopter phenomenon is clearly the result of an electrostatic, not an electromagnetic, field.

 

[Rick Christopherson]

If we connect a resistor between the two bodies, electrons will flow from the more negative body to the more positive body. From an elementary perspective, it may seem that the diagram below is not a complete circuit. There is no "loop". Doesn't a circuit have to be a loop?
===============
A little redrawing will illustrate that this is indeed a complete circuit from one side of a voltage source to another. There is no difference between the drawing above and the drawing below. They are completed circuits.

The above drawing is a completed circuit with one voltage source and one resistor. On that note, so is the second drawing.

Umm, Didn't you realize that the current flow in both of your pictures was in the same direction?

These pictures do not represent a closed path (aka circuit) but two parallel paths from one potential to another.

 

[crossman]

HUH? :-? Where is the contradiction?

In post 246 you quoted and bolded this statement which I posted earlier.

"A single conductor between these two charges is a completed circuit."

Then you posted this refering to the bolded statement:

"This is all I have been trying to say since the very beginning."

So you agreed with the statement and you agreed that there is a completed circuit.


Then, in post 253 you posted this:

"If you have two isolated bodies with unequal charge, and you connect them with a wire (resistor), where is the return path that everyone has been saying must exist?"

and in post 251 you posted this:

"A circuit is defined as a ?Closed Path?... A single wire between two circuit elements is defined as a ?Network?, but it is not a circuit until you close the path."

So on one hand you agree that there is a complete circuit between two remote, unequal charges connected by a single conductor, and then on the other hand, you argue that it is not a complete circuit.