[Elecraft] Current Flow on Copper Strips - a Question

[Wes Stewart]

"When skin effect is present, the current is always redistributed over the 
conductor cross section in such a way as to make most of the current flow where 
it is encircled by the smallest number of flux lines.  This general principle 
controls the distribution of current irrespective of the shape of the conductor 
involved. Thus, with a flat strip conductor (figure reference not shown) the 
current flows primarily along the edges, where it is surrounded by the smallest 
amount of flux, and the true or effective resistance will be high because most 
of the strip carries very little current.  (A reference to the missing figure) 
makes clear that it is not the amount of conductor surface that determines the 
resistance to alternating current but rather the way in which the conductor 
material is arranged."


On 4/26/2018 6:35 PM, Dauer, Edward wrote:
>      Since I don't know what precedes the word "thus" in the quotation below I would ask if someone could explain this phenomenon for me.
>
> I am trying to visualize this with a thought experiment.  In an earlier post someone (Skip?) mentioned that early transmission lines were sometimes hollow copper tubes, to respect the fact that AC flows only on the outside of a conductor.  So, imagine a hollow tube carrying RF (which may approximate the fast rise and fall times of a high voltage strike).  Current is flowing all over the surface, I gather.  Now squeeze the tube along its length so that a cross section becomes an ever flatter ellipse.  At the last instant squeeze it so that the sides are in contact with each other.  What happens to the current flow as that squeezing occurs?  Is it still all around the squished tube until the instant the two sides join?  And then it all flows primarily along the edges of the now flat conductor?  Howcome?
>
> Tnx,
>
> Ted, KN1CBR
>      
>      
>      ------------------------------
>      
>      Message: 3
>      Date: Wed, 25 Apr 2018 18:45:39 -0700
>      From: Wes Stewart <wes_n7ws at triconet.org>
>      To: elecraft at mailman.qth.net
>      Subject: Re: [Elecraft] OT: Grounding Question
>      Message-ID: <a75f6274-fbad-d203-7874-245f94bf5f6e at triconet.org>
>      Content-Type: text/plain; charset=utf-8; format=flowed
>      
>      Radio Engineering and Radio Engineer's Handbook are two different critters.? My
>      copy of Radio Engineering is the third edition and the pertinent information is
>      on p.20.
>      
>      To partially quote: "Thus, with a flat-strip conductor, the current flows
>      primarily along the edges."
>      
>   
>
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