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How do electrons find the “path of least resistance”? [video]

276 pointsby GavCoabout 2 years ago

14 comments

kuonabout 2 years ago
What is &quot;cool&quot;, (or a challenge if you design PCB like I do), is that this is not true for alternating current.<p>For example, if you have a track that does a L on top side, and copper plane on bottom side, with an alternating signal, the return path will follow the L and not go back in a straight line.<p>Those links have some explanations:<p><a href="https:&#x2F;&#x2F;resources.altium.com&#x2F;p&#x2F;what-return-current-path-pcb" rel="nofollow">https:&#x2F;&#x2F;resources.altium.com&#x2F;p&#x2F;what-return-current-path-pcb</a><p><a href="https:&#x2F;&#x2F;www.nwengineeringllc.com&#x2F;article&#x2F;how-to-design-your-pcb-return-current-path.php" rel="nofollow">https:&#x2F;&#x2F;www.nwengineeringllc.com&#x2F;article&#x2F;how-to-design-your-...</a><p><a href="https:&#x2F;&#x2F;electronics.stackexchange.com&#x2F;questions&#x2F;360472&#x2F;real-current-return-path" rel="nofollow">https:&#x2F;&#x2F;electronics.stackexchange.com&#x2F;questions&#x2F;360472&#x2F;real-...</a>
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shagieabout 2 years ago
This reminds me of the Shannon switching game ( <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Shannon_switching_game" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Shannon_switching_game</a> )<p>&gt; Two players take turns coloring the edges of an arbitrary graph. One player has the goal of connecting two distinguished vertices by a path of edges of their color. The other player aims to prevent this by using their color instead (or, equivalently, by erasing edges). The game is commonly played on a rectangular grid; this special case of the game was independently invented by American mathematician David Gale in the late 1950s and is known as Gale or Bridg-It.<p>That game, if modeled as an electrical circuit of resistors has the property that the best play is the one with the most voltage across it.<p><a href="https:&#x2F;&#x2F;boardgamegeek.com&#x2F;boardgame&#x2F;123102&#x2F;bird-cage" rel="nofollow">https:&#x2F;&#x2F;boardgamegeek.com&#x2F;boardgame&#x2F;123102&#x2F;bird-cage</a><p>&gt; The game&#x27;s original incarnation was as a machine built by the game&#x27;s designer, noted engineer Claude Shannon. The machine would choose its&#x27; move by measuring electrical resistance between its&#x27; sides of the square and would reportedly win &quot;almost always&quot; when making the first move.
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photochemsynabout 2 years ago
Gravity is the driving force behing the flow of water in this example, and a static electromagnetic field (in a DC circuit at least) is the driving force behind the flow of electrons. The water can do work on physical object (waterwheels, etc), and the electrons can do work on electrical loads (lightbulbs, etc.).<p>However the static electromagnetic field in the DC circuit propagates through the material at near light-speed once the battery switch is thrown, which is a bit different. I suppose if you could throw a switch and turn gravity on or off it would be a closer analogy, i.e. the idea would be to fill the (sealed) maze with water in a zero-g environment (it would fill everywhere equally, comparable to the electons in the conductor with the power off), then turn on the gravity (or the pressure differential for the pipe version) and see what happened.
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jagrswabout 2 years ago
The video is interesting, but I suspect, that the author is making some subtle errors at places. Tho I&#x27;m not 100% sure, last time I analyzed those subject was at BsC&#x2F;MsC courses at my uni.<p>E.g. he says something to the tune of<p><pre><code> electrons take a few ns. running around, and then settle down in the maze. </code></pre> IIRC electron flow in a medium is relatively slow, something on the order of centimeters per second. So it&#x27;s not electrons which settle some potentials by moving quickly, but the electric potential finds its equilibrium. And it finds its equlibrium by electrons exchanging virtual photons (carries of electromagnetic force)?
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imtringuedabout 2 years ago
They take all paths weighted by resistance.
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lucas_membraneabout 2 years ago
Not all the electrons follow the path of least resistance. The currents in parallel paths are in inverse proportion to the resistances of the respective branches.
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sisterabout 2 years ago
I hope loose your sense of wonder...never settle for path of least resistance... And I hope you still feel small as you stand beside the ocean ..when ever one door closes I hope one more opens I hope you get your fill to eat but always keep that hunger .. ps dance in the reign....challenge has made to the finish line ilevennif I did not pass go. .
strstrabout 2 years ago
Nothing in this video is super groundbreaking if you’ve taken a typical physics class that includes some E&amp;M.<p>That said, the demonstrations are pretty compelling and well executed. I particularly liked the use of an IR camera to visualize the resistive power loss in the maze. Super cool.
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Animatsabout 2 years ago
Summary: &quot;It&#x27;s like a whole bunch of stagnant lakes connected to the same river&quot;.
bitLabout 2 years ago
Can you solve arbitrary traveling salesman problem with that? There is only a polynomial number of required laser cuts (n nodes, n * (n-1) edges) and the source can be next to sink with a fake 0 edge between them.
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low_tech_punkabout 2 years ago
Great use of analog computer! Makes me think this Veritasium espisode: <a href="https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=GVsUOuSjvcg">https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=GVsUOuSjvcg</a>
markjspiveyabout 2 years ago
electrons don’t, electricity does .
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jbverschoorabout 2 years ago
The final experiment at the end was cool. It really is exactly like water
Etrnl_Presidentabout 2 years ago
This also applies to economics.