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| "Veritasium" (YT) - "The Big Misconception About Electricity" ? |
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| HuronKing:
--- Quote from: adx on March 13, 2022, 12:25:22 pm ---On one hand yes, a basis. But what is a basis? Theoretical? Foundational? Occupational? --- End quote --- That the phenomena observed is explicable and predictable. Engineers just use that phenomena to solve problems. --- Quote ---Selenium cells were in use 30 years before that, and in futuristic 'practical' applications like the photophone in the same year as Einstein's paper: https://en.wikipedia.org/wiki/File:Ernst_Ruhmer,_Technical_World_cover_(1905).jpg These cells were also apparently in use as rooftop PV solar in 1884: https://en.wikipedia.org/wiki/Charles_Fritts (Although I am a bit sceptical of the references because some claim it was thermopile based - Wikipedia isn't always right.) --- End quote --- Your story about selenium is missing the preamble - namely physicists doing experiments on selenium, making determinations of its behavior, and making predictions about future behavior: https://books.google.com/books?id=JbNK9lRLHPEC&pg=PA67#v=onepage&q&f=false https://royalsocietypublishing.org/doi/pdf/10.1098/rstl.1877.0009#:~:text=The%20light%20of%20an%20ordinary%20lucifer%2Dmatch%20was%20found%20to,Effect%20of%20Moonlight%20on%20Selenium. They didn't have quantum theory yet to explain its behavior (which doomed them to never be terribly practical) - but let's not necessarily suggest Maxwellian physical theory had nothing to do with it either... Maxwell was one of the people doing experiments on solar cells! --- Quote ---It's a weak argument to say that the subsequent quantum theory gave basis for extant devices and applications - even if those applications later benefited enormously. Just because it was noticed and described, doesn't mean it works any different at any time. The theory becomes a guide for unchanging empirical behaviour, once people are on its scent. I don't accept that this 'scent' is academic theory, except in special cases where it is. --- End quote --- Those devices weren't innovated much further without the 'scent' of academic theory. Maybe it would've happened anyway (we can never know of course) but let me tell a story: In one of my advanced photonic courses there was pretty rampant cheating amongst a group of students. The professor was, for better or worse, too nice a guy to actually do anything about it. But, he did say this about it after an exam, "In science... there is an infinite number of wrong answers but only one, maybe two, right answers... so how come you all got the same wrong answer?" I guess they were somewhat incompetent at cheating which is why he didn't care. >:D My point in this story is that we can, and have, fumbled our way forward by 'brute forcing' or 'advanced hacking' as you put it earlier to create inventions and slog technology forward. But there are a lot more wrong answers than there are right answers. You could try 1000 different materials to build something... but applying just a little physics takes one forward in a BIG way. While the first 1925 FET patent didn't get noticed, it's remarkable how clearly Lilienfeld defines its operation is based on nascent quantum theory, https://worldwide.espacenet.com/patent/search/family/035202468/publication/US1745175A?q=pn%3DUS1745175 "The basis of the invention resides apparently in the fact that the conducting layer at the particular point selected introduces a resistance varying with the electric field at so this point; and in this connection it may be assumed that the atoms (or molecules) of a conductor are of the nature of bipoles. In order for an electron, therefore, to travel in the electric field, the bipoles are obliged to become organized in this field substantially with their axes parallel or lying in the field of flow. - Any disturbance in this organization, as by heat inovement, magnetic field, electrostatic cross-field, etc., will serve to increase the resistance of the conductor; and in the instant case, the conductivity of the layer is influenced by the electric field. Owing to the fact that this layer is extremely thin the field is permitted to penetrate the entire volume thereof and thus will change the conductivity throughout the entire cross-section of this conducting portion." --- Quote ---I accept the leap-frogging effect, I accept the greater advances, I even accept that a technology could stall at some point without the theory. But I can't accept that the latter is unavoidable, and I think that things like Wikipedia articles which begin and end on the equations are a disservice to the field(s) --- End quote --- I can only go off what I know about history. The unfortunate thing about history is that there is no "control" in the experiment of our history to tell whether something would or would not have happened without X-Y-Z. What I do know is that MASSIVE technology advancements ALWAYS follow a PARADIGM SHIFT (term from my History of Science class) in theory. People have been building mechanical devices for 1000s of years but no one knew how to build really good stuff until Newtonian Mechanics. There is a unique power that the paradigm shift from Aristotelian physics to Newtonian physics gave humanity. I'd say that's the most compelling case that technology absolutely stagnates until a MUCH better theory comes along. I'm not suggesting people in Aristotle's time were stupid or didn't make some clever engineering decisions... but when you believe objects fall at different rates, even while practically true most of the time, is fundamentally limiting in what anyone tried to create. And I'd say we got the ol' 1-2 punch from the paradigm shift from Maxwellian Theory (that made global, wireless communications and AC power possible) to Quantum Theory (that made transistors possible, enough said!). I don't know what the next paradigm shift is going to be... maybe quantum gravity? Don't know. But it'll be exciting! --- Quote ---The latter is what I meant. That the iPhone doesn't definitively owe its existence to predictions of physics and academic process, unless you want to take the position that any one link in the chain could be undone if it wasn't for some glorious crystal of theory (like Maxwell's equations, say, or something which 'makes' fets work especially at 5nm). People tend to push through those kinds of things if they can see a way past. Or if you want to say we wouldn't have the iPhone today, which is obvious. --- End quote --- I'm not certain we'd have the iPhone ever. There are a lot of 'wrong' ways to make an iPhone. It's much more likely we'd find all the wrong ways before the right ways without a governing theory to predict what to do in the next experiment... which is in the physics. --- Quote ---I certainly don't want to say physics had no part or is dead. The only thing I want to target is this (I assume) taught notion that science begat physics begat engineering that doesn't seem to exist outside of academia and governmental ivory towers. The commercial world is completely indifferent to that, and simply assumes that physics is one of the parts of engineering. --- End quote --- I work in both academia and the commercial world. The predecessor to ABET defined engineering as, "The creative application of scientific principles to design or develop structures, machines, apparatus, or manufacturing processes, or works utilizing them singly or in combination; or to construct or operate the same with full cognizance of their design; or to forecast their behavior under specific operating conditions; all as respects an intended function, economics of operation and safety to life and property." Emphasis mine. So, if physics isn't foundational to what we do, what even is engineering??? :o Perhaps it might be helpful if you elucidate on that question. ^-^ --- Quote ---Claims that "physics had to come before technology" can be made arbitrarily, eg fax machines might have stepper motor drivers, image sensor chips and even lasers. But when it's said that optical fax existed in the late 1800s, those claims need adjustment. They might still be correct, but it doesn't have much meaning. --- End quote --- I'm not sure what you're saying here. --- Quote ---Re Heaviside, he usually is called a physicist, but before that was recognised, he was shunned by just about any institution (but not person) that could exist. He was an electrician (possibly more in line with an electrical engineer today). Patenting the coaxial cable sounds awfully like engineering to me. So do eschewing some mathematical rigour, and getting into spats with an ignorant boss. And so on. My point being that this distinction can be imaginary (or perhaps arbitrary). Denying physics would be completely silly, but I don't think that's what I'm saying. It's certainly not what I want to suggest or portray. --- End quote --- You're getting close here. :) Heaviside is a strange but interesting case though so I'd rather speak more generally towards the end of my post. The whole 'physicists vs engineers' vibe I've seen around the net since Electroboom's KVL videos is really what's riled me to be more outspoken in the various forum I've lurked in. It's gotten a resurgence since Veritasium's video for different reasons. And in my line of work as both a working engineer in industry AND someone educating future engineers from within academia, it makes me sad to see these kinds of ridiculous attitudes filtered down into my students. :-// Probably the real "physicists versus engineers" debate is whether to use i or j for the complex number. And the answer is obviously j because what the heck do you call current then? :box: |
| penfold:
--- Quote from: HuronKing on March 14, 2022, 01:55:45 am ---[...] Probably the real "physicists versus engineers" debate is whether to use i or j for the complex number. And the answer is obviously j because what the heck do you call current then? [...] --- End quote --- Let's not forget that engineers and physicists have very different job descriptions. That doesn't necesarily prelude a person of either primarily physics, primarily engineering, or primarily mathematics background from working either job function or using i, j, I, J, i, j, I or J as a complex unit or 'current-(density)' variable. The interesting question there would be: which scientific descoveries arrived from which practice of which principals by a practicioner of which background? |
| aetherist:
--- Quote from: adx on March 14, 2022, 01:27:12 am --- --- Quote from: aetherist on March 13, 2022, 10:07:27 pm ---I suppose that the simplest answer is that the irregularities in the thin skin of the wire is much the same as the irregularities deeper in the wire. But why would electons (ie photons) be slowed by irregularities in the skin of the wire? --- End quote --- That doesn't work if the surface is plated with a highly conductive metal, eg silver on steel. The resistance except at very high frequencies (skin effect) is that of the bulk steel wire. --- End quote --- Do u know of any papers re tests re the DC resistance of copper clad steel wire (or silver or gold)? Hmmm – the DC resistance of steel clad copper wire would be even more interesting. https://en.wikipedia.org/wiki/Copper-clad_steel https://mwswire.com/copper-clad-steel-wire/ https://publications.waset.org/10011187/conductivity-and-selection-of-copper-clad-steel-wires-for-grounding-applications --- Quote from: adx on March 14, 2022, 01:27:12 am --- --- Quote from: aetherist on March 13, 2022, 10:07:27 pm ---Problem 6. Electons are a surface dweller, hence u would think that doubling the dia of a wire would halve the resistance. If doubling the dia results in a ¼ resistance then electons are in trouble. For DC current. --- End quote --- Well spotted. --- End quote --- Looking ahead for good excuses. If new (electon) electricity was very sensitive to temperature then that could explain the further doubling of resistance, to make it 1:4 instead of 1:2 (if indeed the 1:4 exists). |
| TimFox:
From the major manufacturer of copper-clad steel wire: https://www.copperweld.com/application/files/7115/3833/2605/Welded_Copper-covered_Steel_CCS_Strand_Electrical.pdf |
| aetherist:
--- Quote from: TimFox on March 14, 2022, 09:29:28 pm ---From the major manufacturer of copper-clad steel wire: https://www.copperweld.com/application/files/7115/3833/2605/Welded_Copper-covered_Steel_CCS_Strand_Electrical.pdf --- End quote --- The tables for ohms per mile show lower resistance for DC than for 60Hz. That is the opposite of what might be expected. It must be a quirk of the temperature ratings or something. Anyhow, it tends to support my electons. I wonder if there are any papers that deal with thickness of copper (or silver or gold) cladding, i mean very very thin cladding/coating. |
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