General > General Technical Chat
Sick of ridiculous KVL infighting
<< < (8/15) > >>
bdunham7:

--- Quote from: SiliconWizard on January 14, 2022, 06:16:09 pm ---And, Lewin's demonstration itself - oh I know, let's not get into that all over again - was flawed IMHO. Let's put another coin in the machine. ;D

--- End quote ---

The demonstration was great.  His explanation contained clever elements of misdirection.  I think everyone willing to consider reasonable explanations has already figured it all out and left the building--at least in that thread.  As for what remains, I've seen contested divorces that were less contentious.  The whole thread is now even sillier than the can't-go-faster-than-tailwind guy, and that's saying a lot.
Siwastaja:

--- Quote from: Simon on January 14, 2022, 12:30:14 pm ---My memory is that Lewin demonstrated that the law did not hold, but gave no further explanation as though he had proved someone wrong. As a lesson that is a failure.

--- End quote ---

If you actually watch it, there's nothing special about it: typical demonstration, with explanation, but it's math heavy; you need to have solid understanding in the math.

It's also series of lectures, not hit-and-run. Students are also assumed to follow a textbook.

Remove small part of it from context, without understanding surface and line integrals and curls and whatnot, and the result is what it is.
snarkysparky:

--- Quote from: bdunham7 on January 14, 2022, 05:29:52 pm ---
--- Quote from: instrumental on January 14, 2022, 02:35:06 pm ---Both sides are correct up to a point; then, one answer strongly dominates the other. It's a matter of knowing when certain approximations can be made and when those approximations no longer hold.

--- End quote ---

I don't think that's true in the Lewin/KVL 'debate'.  It's not like classical physics vs modern physics or anything like that.  There's a stark disagreement over whether the voltage between two points in a given apparatus is a uniquely defined single number or can be different numbers depending on 'the path'.  The debate devolves from there.

--- End quote ---

Faradays integral law says the line integral of electric field around any closed path is equal the the time rate of change of flux enclosed by the path.
What the path is is not specified. 

So I vote for electrical potential in non time changing fields to be path independant.


bdunham7:

--- Quote from: snarkysparky on January 14, 2022, 08:38:40 pm ---Faradays integral law says the line integral of electric field around any closed path is equal the the time rate of change of flux enclosed by the path.
What the path is is not specified. 

--- End quote ---

Yes, but Faraday's Law does not itself directly represent a physical phenomenon.  It is simply a provable result of integral calculus that all paths that completely enclose a specific amount of changing flux will have a particular amount of total EMF around that path.


--- Quote ---So I vote for electrical potential in non time changing fields to be path independant.

--- End quote ---

I'm not sure I follow the reasoning. 
snarkysparky:
reasoning is that IF faradays integral law is correct the result is path independent.   Old man Faraday didn't say what path is to be taken.

EQ 4 

https://hep.uchicago.edu/cdf/frisch/p142/Purcell_Chapter2.pdf


Navigation
Message Index
Next page
Previous page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod