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March 15th, 2017, 09:14 AM   #11
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Quote:
 Originally Posted by Loren Kirchoff's laws apply to electrical circuits. Mankind's electrical grid is such a circuit. Other than having a spherical topology, it is a system of active wires which embodies loops and nodes on the large scale. Does our current on Earth's surface have a preferred direction or density? Is its stability affected by natural events resulting in blackouts? (By "Earth" I am not referring to "ground.")
I decline to argue with you, since your mind is clearly made up.

I would, of course, be open to your posted proof of this over general statement.

Quote:
 Kirchoff's laws apply to electrical circuits.

March 15th, 2017, 09:15 AM   #12
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Sorry... just noticed this post...

Quote:
 Originally Posted by Loren I was considering all man-made electrical networks, basically +/- 1000 meters above and below the Earth's surface. Think of where wires are present. By Kirchhoff's laws, most currents would cancel where there are nodes, and voltages would cancel where there are local loops.
Yes, electricity grids are just large electrical circuits and therefore obey Kirchoff's laws.

Quote:
 I guess that in the oceans or e.g., North Korea, there would be few nodes or loops, thus the nodes would be mostly simple, and the loops large. Advanced nations' networks might form a Faraday cage over them.
Naaah... the wires are insulated and there are over-voltage protections in the case of a surge (like a lightning strike or a component failure). The EM waves created by passing currents through wires is annoying because there is energy lost by the induction of currents in multiple nearby conductors, but they don't have useful information content worth intercepting. Maybe you're conflating electricity with radio/microwave communications?

Even if you pass a monumentally large current, ocean currents have a very, very low current density because they are so large, so the impact on swimmers is going to be stupendously weak.

Quote:
 North Korea would be vulnerable to remote sensing or clandestine interference with their relatively simple electrical systems.
This sounds like some sort of silliness from a Tom Clancy novel. It's really very easy to take down an electricity network... just blow up the power plants or sever the connections they have to the grid (indeed, power stations are key strategic locations in war-time).

Power distribution in North Korea is probably not much more different than power generation and distribution elsewhere. Electricity grids are old technology and most of the innovation is about energy efficiency of components, decentralisation of the sources of electricity (so-called move to 'micro-grids' or 'electricity clouds'), effective peak demand response and the move to renewable energy sources. When electrical engineers talk about security of an electrical supply, they're typically referring to theft rather than vandalism.

Quote:
 Current-generated magnetic fields would be more dense over advanced nations. Weak areas may prefer clockwise or counterclockwise current, depending on forces within the loop, mostly those of Earth's dynamo and the solar wind. Blackouts often appear due to the finite speed of light over a loop or on too complicated a node.
This is daft. Did you read this from one of those fiction magazines again?

 March 15th, 2017, 11:38 AM #13 Senior Member   Joined: May 2015 From: Arlington, VA Posts: 348 Thanks: 26 Math Focus: Number theory Thanks, Benit13, with the exception of Kirchoff's laws, my post is too much late-night speculation.
March 15th, 2017, 03:19 PM   #14
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Since you are both so hung up on the universality of Kirchoff's Laws, perhaps you would like to explain how to apply these Laws to this simple but complete circuit?

Have either of you seen Professor Lewin's (MIT) famous lecture as to why Faraday was right and where Kirchoff was inapplicble?

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March 15th, 2017, 04:48 PM   #15
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If you don't like the use of digital circuits as examples, here is a power connection circuit, that can't be solved by Kirchoff's Laws.

What is the voltage at A and the current through the resistor?

I have shown batteries, but this issue is faced every day by power plant engineers as most plants need to employ multiple generators in parallel.
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 March 15th, 2017, 07:14 PM #16 Senior Member   Joined: May 2015 From: Arlington, VA Posts: 348 Thanks: 26 Math Focus: Number theory I seem to be in good company, so I will naively guess the voltage between node "A" and ground (that across the resistor) is (1/(1/12+1/6)) Volts=4 Volts , and the current through the resistor is V/R=4 Volts/10 Ohms=.4 Amps. Actually, what happened to the internal resistance of the batteries? Being simple, I like "counterintuitive." Please draw more legibly.
March 15th, 2017, 07:40 PM   #17
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Quote:
 Originally Posted by Loren Being simple, I like "counterintuitive." Please draw more legibly.
Legibility is fair call. But what do you mean "I like "counter intuitive""...?

 March 15th, 2017, 09:59 PM #18 Senior Member   Joined: May 2015 From: Arlington, VA Posts: 348 Thanks: 26 Math Focus: Number theory No insult intended. Listen to Prof. Lewin on YouTube when he mentions "nonintuitive." It's neat to try puzzles like "The Game Show Problem": Game Show Problem | Marilyn vos Savant. It is one of the great examples of counterintuitive logic, simple yet profound. That's where most great questions and answers can be found, and problems one can focus on. Again, refer to Prof. Lewin on Kirchoff vs. Faraday re intuition. Apparently your problem may be counterintuitive to Kirchoff's laws. But I diverge from your inquiry.
March 16th, 2017, 02:15 AM   #19
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Quote:
 Originally Posted by Loren Thanks, Benit13, with the exception of Kirchoff's laws, my post is too much late-night speculation.
No worries, it's all good fun!

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