Author Topic: "Veritasium" (YT) - "The Big Misconception About Electricity" ?  (Read 263909 times)

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Offline bsfeechannel

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Re: "Veritasium" (YT) - "The Big Misconception About Electricity" ?
« Reply #675 on: December 23, 2021, 06:02:54 pm »
Who is the "father mocker"?
Who else? Old Nick. A.k.a. Ahriman, in certain parts of the world.

EDIT: Photoshopped image removed by admin. He is referring to Mehdi.

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Why the insults?
"Faffing around the edges of physics" is not an insult? OK. I'll update my definition of insult. Thank you, Dave.

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That's all basic engineering transformer theory, just jump to the transformer formulas and you are good to go for most cases. For specific useage cases, other formula exist. Little need for any advanced maths or physics.

Of course I don't resort to my videos when I need to design a transformer. With practice you do things by heart. No need for formulas to quickly slap together a fixed voltage power supply, or an op-amp circuit, or a simple combinatory logic circuit. No use of KVL/KCL or Ohm's law. I already know the values, the component specs, etc. I don't even have to consult datasheets. It's all second nature.

However, if my preconceived notions are challenged on sane scientific grounds, I don't automatically assume that the one who brought it up is wrong and launch a campaign to discredit the person.

We, engineers, don't do that. At least I don't. And I've known a whole slew of engineers who don't exhibit that kind of behavior.

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And I'm NOT saying it's not good to know where it all comes from. Go and read Hayt and see how deep the rabbit hole goes. But like I said, it's not a text you'd pick up to design your transformer.

That's not what you say in your videos. Since with practice we don't need to resort to the fundamentals, NEVER resort to the fundamentals. This is for physicists or bored engineers. Keep trying to solve every problem with the rules of thumbs, approximate models, fixed formulas, etc., that we developed to streamline our design process. That's engineering 101, you say.

No, that's not. This engineering 50.5.

These streamlined practices come with trade-offs. They take into consideration several limiting assumptions to work. Assumptions that we tend to forget. That's the whole point of the engineering degree: never forget where your shit comes from, and resort to the fundamentals when it doesn't work. You don't want to waste your time trying to employ a tool crafted for a specific problem that's not what you're having.

That's engineering 101 right there.

KVL? Cool. Helps a lot. Caveat: it comes with assumptions. Ignore them when KVL doesn't work and you'll came a gutser. Flow of energy? Follow the wires. Caveat: it's all in the fields. And so on and so forth.

What you end up doing, willingly or not, is a disservice to engineering, because you're omitting an important part of engineering PRACTICE and even worse teaching that to beginners. The consequences we can already see on this very forum where it is impossible to show someone where KVL fails that people think that we are Lewin's rooters and the discussion can't go ahead.

If Mehdi, or you, want to poke fun at physicists or at engineers who care to really understand what they're doing, be my guest. You decided to rely on viewership for a significant part of your income. So, if you want to produce sensationalistic content, I don't have a problem with that. In fact I'm happy with your success. But, you'll of course read comments you probably don't want to on your respective forums. Don't expect unanimity among engineers in this case. Be prepared for it.
« Last Edit: December 23, 2021, 10:28:27 pm by EEVblog »
 

Offline SiliconWizard

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Re: "Veritasium" (YT) - "The Big Misconception About Electricity" ?
« Reply #676 on: December 23, 2021, 06:06:08 pm »
BTW, after talking with Derek at length on the video it was clear that there was no intentional troll toward engineers with the question. He genuinely thought the question would help his target audience of people who have learnt some basic electicical theory and weren't really taught how EM fields related to it later on.

Yup, that looked like it was his point. Good that you have confirmation.
He also told several times that he knew he would get called on it. All this was entirely predictable.

With the testing he's doing now I pointed out the potential probing issues like with the AlphaPhoenix test, and how testing this is guaranteed to drag the engineers further into the debate.
And how any testing video is bound to be messy from an explanation point of view.

Yep yep yep. Seems like many people, here and elsewhere, are largely underestimating the challenges of proper probing here.
Remember that probing was also a large part in the "debate" about Kirchhoff laws and Lewin's experiment.

Measuring in general is one of the trickiest parts of experimental physics.
 

Offline bdunham7

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Re: "Veritasium" (YT) - "The Big Misconception About Electricity" ?
« Reply #677 on: December 23, 2021, 06:08:41 pm »
I also tried to explain why the dual transmission line model cannot let you see correctly what happens in the first nanoseconds because it's literally zero dimensional in the transverse direction.

I'm not aware of any dispute over this issue.  You keep mentioning it as if nobody believes you, but we all get that.  Really.  The transmission line models the longer-term behavior over the whole circuit--microseconds or seconds.  The first 10 nanoseconds--or more--are messy and highly dependent on minor geometric variations.

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Look at Ben's simulation: do the two legs behave like ordinary transmission lines? Shouldn't you be seeing a symmetric red-.green aura going back and forth along the top and bottom conductors? While in this circuit the red-green aura travel along the bottom conductors first (whith a faint ghost on the top one) and then gets back on the top one? In my eyes this is a radically different behavior that tells me that field simulation is the way to go.

Well, Ben acknowledges that the legs are 'basically transmission lines' but with that geometry and scale I would not expect 'nice' results nor do I see a reasonable way to verify them through physical experiment.  I would like to see a simulation of a physical model that can be built experimentally.  Then we can compare.  AlphaPhoenix did an experiment, but obviously we can't model the short-term initial response and I'm not sure that is the interesting issue.  I think the long term--say 5us--could be modelled.  The relatively flat, even response he got for the first L/c time is worth thinking about.  It looks 'transmission line-ish' to me.
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 

Offline bsfeechannel

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Re: "Veritasium" (YT) - "The Big Misconception About Electricity" ?
« Reply #678 on: December 23, 2021, 06:48:21 pm »
BTW, after talking with Derek at length on the video it was clear that there was no intentional troll toward engineers with the question. He genuinely thought the question would help his target audience of people who have learnt some basic electicical theory and weren't really taught how EM fields related to it later on.

Derek is successfully introducing Maxwell's equations and the Poyinting theorem to a lay audience, while we are discouraging engineers to understand the concept.

 :palm:

Look what we've become.
 

Offline bsfeechannel

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Re: "Veritasium" (YT) - "The Big Misconception About Electricity" ?
« Reply #679 on: December 23, 2021, 06:53:52 pm »
That's a pretty good introductory video for someone with little or no idea on transformer basics, or even a run-through for someone who is rusty.

Thank you.

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But it isn't the sort of thing you'd reach for when you suddenly need to design a custom transformer for some specific purpose and you don't do it on a regular basis.  You'd look for a reference like this instead.  And I'm fairly sure that the experienced engineer that wrote this article knows every single thing you have in your video. 

https://talema.com/smps-transformer-design/

I published these videos because I ordered a custom transformer and the technician with whom I discussed the specs couldn't understand my requirements. He was stuck to predefined "best practices" that he didn't quite get why they existed.

So I decided to show where these practices come from, and how you can safely "break" them.
 

Offline Howardlong

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Re: "Veritasium" (YT) - "The Big Misconception About Electricity" ?
« Reply #680 on: December 23, 2021, 07:04:22 pm »

Derek is successfully introducing Maxwell's equations and the Poyinting theorem to a lay audience, while we are discouraging engineers to understand the concept.

Straw man. No one's discouraging anyone from trying to understand either.

Some of us are just saying that for most EEs, there is no practical need to resort to directly using either. I know you enjoy using them as tools to make you classes more challenging, and good for you. But for the vast majority of EEs, that is all they will ever be: a challenging class exercise.
 
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Offline EEVblog

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Re: "Veritasium" (YT) - "The Big Misconception About Electricity" ?
« Reply #681 on: December 23, 2021, 10:07:58 pm »
With the testing he's doing now I pointed out the potential probing issues like with the AlphaPhoenix test, and how testing this is guaranteed to drag the engineers further into the debate.
And how any testing video is bound to be messy from an explanation point of view.

ep yep yep. Seems like many people, here and elsewhere, are largely underestimating the challenges of proper probing here.
Remember that probing was also a large part in the "debate" about Kirchhoff laws and Lewin's experiment.
Measuring in general is one of the trickiest parts of experimental physics.

Indeed.
And although I don't have photos of his setup, from what he told me I think probing might be extra tricky.
I think if he releases a video that doesn't properly electrically isolate the switch and load sides, that will just lead to even more debate. Or as it's gotten to here, what's happening inside the resistor load. It's impossible for him to win. Although I think much of his audience will just be happy to see something with the first few ns.
Yes, the Mehdi/Lewin debate was essentially about the setup, not the fundmental physics.
« Last Edit: December 23, 2021, 10:30:16 pm by EEVblog »
 

Offline EEVblog

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Re: "Veritasium" (YT) - "The Big Misconception About Electricity" ?
« Reply #682 on: December 23, 2021, 10:19:01 pm »
Derek is successfully introducing Maxwell's equations and the Poyinting theorem to a lay audience, while we are discouraging engineers to understand the concept.
Straw man. No one's discouraging anyone from trying to understand either.
Some of us are just saying that for most EEs, there is no practical need to resort to directly using either.

And not every content producer has to produce content that's all things to all people all the time. It's OK to make content (or have a discussion) that caters to a certain audience level, whilst avoiding the deeper levels, or vice-versa. Derek's video itself left out all mention of various other ways to look at the problem, as has been discussed in length here and in many response videos.
Both discussions belong here, the problem is some people can't seem to appreciate and separate the two and think that only one way has any worth. And some seem surprised when confronted with an opinion that it's "faffing around the edges of physics" to consider what happens inside the resistor before the voltage can be measured.

Like I've said before, if Derek didn't have the question in there, this thead likely wouldn't exist, and there wouldn't be any response videos. Most of us would have just said "cool video on Maxwell and Poynting" and that would be it. But when you introduce a practical engineering question, and not mention any practical engineering ways of looking at it or coming up with the answer, then you invite the lively debate we have seen.
« Last Edit: December 24, 2021, 01:47:32 am by EEVblog »
 

Offline adx

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Re: "Veritasium" (YT) - "The Big Misconception About Electricity" ?
« Reply #683 on: December 24, 2021, 06:11:49 am »
I'm at a loss to describe my feelings on KCL, or even what it is. Fortunately I don't remember. It's probably at the core of simulator technology, in addition to matrices. Something to do with things adding up to zero, which sounds awfully like circuit analysis in model land. The type of circuits we draw with long lines representing zero length connections.


- Speechless -


I troll in jest. But not really, because it's true.

There's a KVL? That is the hint I needed to remember what the "C" is for in KCL, it might be coming back to me a bit more. My mind was going to potassium chloride, wondering if the standard production process is carefully dropping a kilo of potassium into a bucket of hydrochloric acid and hoping it doesn't fizz too much. The name Kirchoff I do remember, as in "good day sir, I need to sneeze, would you be so kind as to lend me your handkirchoff ... very well, you can have it back now" - an inter-pandemic conversation perhaps from a century gone by. I remember it in the plural "laws". There was Thevenin and Norton, I do know what those are, but even now it reminds me of the stuff of dreariest lecture - dreary being a contraction of "dry theory" (I assume). My mind still drifts to a brand of silicon carbide doused icecream (when I was little I used to dip my icecream in the beach for extra crunch, so it has physical precedent). You get the idea - this stuff was passing monotone and I forgot it, through cramming for exams and decades of entire disuse.

Having done the right thing by my educators (by focussing solely on their material for 3 days and actively forgetting all other topics) and by myself (by forgetting something that has proven to be literally useless to me and all those around me) I can feel a sense of achievement and enlightenment - bsfeechannel put it best in the words "pride of ignorance". Perhaps the highest principle of engineering - to know that you don't know what you don't know. A badge of honour to be worn by those who have toiled through the years to arrive at a place where knowledge works and even one's mistakes seem less frequent.

I genuinely don't remember what KCL and KVL are, beyond that stated above. Taking a hint from "things adding up to zero", and without looking I'll guess:

guestulate 1: the sum of all currents into and out of a node is zero.

guestulate 2: all voltages around a loop add to zero.

I've got a feeling this is right, but remember I am unqualified to take a side in an argument (well, technically not, but that's splitting hairs). I have guessed at my knowledge. But I can make some observations on this interpretative ignorance:

1: All the currents going into or out of a node equals all the current going into and out of a node.

2: The sum of voltages around a loop of by definition zero voltage, is zero volts.

To really boil it down for meaning:

1: Insulators are insulating.

2: 0 = 0.

In the real world, voltages are quantised in irregular discrete levels like 1V8 3V3 5V, 12V, 24V, 48V, 110V and range all the way up to a million volts. A supply rail is established by buying something or designing something like a SMPS, from that all manner of contraptions draw their power, currents flow as a result of series and parallel connections, RF only emits from approved modules, the board rolls through the SMT line, and the customer is delighted.

No, I'm not pleased by that when taken to its button-pressing extreme. But I've never thought of running a 3V3 chip from a -3V3 reg (or really vice versa). I've never known enough to fear current leaking from some insulated node by a magical route. I've never known there was a limit as you move to RF and fields. I simply never took it on board. I learned from what works.

Computers yes. Historians yes. It is interesting in those contexts and should be taught. Not core syllabus, it is not the stuff of understanding and absolutely not real world (in my experience). (To be fair, the lecturer may have done the material right, by saying the academic equivalent of "yeah nah, you'll probably all be using simulators in the future, so you will probably never use this, but this is how they work".)

If I'm wrong in my guesses about KCL / KVL then I mean generally "something like that", and note that not knowing or having them correct has not done me any harm that I know of.
 

Offline adx

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Re: "Veritasium" (YT) - "The Big Misconception About Electricity" ?
« Reply #684 on: December 24, 2021, 12:36:08 pm »
Like I've said before, if Derek didn't have the question in there, this thead likely wouldn't exist, and there wouldn't be any response videos. Most of us would have just said "cool video on Maxwell and Poynting" and that would be it. But when you introduce a practical engineering question, and not mention any practical engineering ways of looking at it or coming up with the answer, then you invite the lively debate we have seen.

Without being primed on how to react, it seems the world has struggled to come up with an answer. It is a question with a wide variety of potential answers and methods, as he knew. He pokes a sleeping bear with power flows outside the wires. But still, you'd think one camp would win out over the other with a technically superior result given all the advances of humanity and technology, but it just hasn't happened. People are running around testing things like it's 1900. It's a bit of a tricky question, but not complex and not beyond human knowledge. It reminded me of that scene in one of the Matrix movies with Neo and the Architect and a whole lot of screens surrounding them, showing the same person with wildly different reactions. It is the first time I've thought about many things from Maxwell to practical relativity in a long time, some things I just didn't know (that magnetism is a relativistic effect). Move over pre-packaged education and media?
 

Offline Howardlong

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Re: "Veritasium" (YT) - "The Big Misconception About Electricity" ?
« Reply #685 on: December 24, 2021, 04:09:17 pm »
It's a bit of a tricky question.

It wasn’t a tricky question, it was a trick question.
 

Offline SiliconWizard

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Re: "Veritasium" (YT) - "The Big Misconception About Electricity" ?
« Reply #686 on: December 24, 2021, 05:21:27 pm »
But still, you'd think one camp would win out over the other with a technically superior result given all the advances of humanity and technology, but it just hasn't happened.

Because that's just not how science works. There is no "truth" that wins. There are just human-made models that fit reality through experiments under certain conditions. Of course models that make no sense and don't pass the test of reproducible experiments are just garbage to throw away. For the rest, it's all relative. As Einstein would say. In other words, we can prove some theories are patently wrong (it just takes one counter-example), but we can't prove anything is "true". We can just have a good level of confidence that we've not been able to prove it wrong so far, and that it appears useful when applied to *some* reality.

People are running around testing things like it's 1900. It's a bit of a tricky question, but not complex and not beyond human knowledge.

The question itself is ill-defined to begin with, which is the main reason for so much debate and people trying to prove things through experiments (most of them having no clue how to conduct those experiments properly, by the way, IMHO.) As I (and others) have said a while ago now, what IS the real question here? Can you state it clearly, and if so, how do the various experiments we have seen so far answer the question exactly? Why is it that people confuse steady-state and transient behavior?

That said, it shows that modeling power transfer using lumped models, while certainly possible, can be pretty tricky. And yes, it's related to the whole previous "Lewin" debate. In the end, some have tried to show that using lumped models was just not possible in some cases, some have tried to prove the opposite. Where is the "truth" that many of us are so eager for? "The truth is out there", as they say. ;D

Oh, and this guy's videos are not too bad:

He made one about Lewin's experiment too.
« Last Edit: December 24, 2021, 05:25:30 pm by SiliconWizard »
 

Offline bsfeechannel

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Re: "Veritasium" (YT) - "The Big Misconception About Electricity" ?
« Reply #687 on: December 25, 2021, 12:28:20 am »
EDIT: Photoshopped image removed by admin. He is referring to Mehdi.

Thank you for getting rid of the "prince of darkness".

By the way, Merry Christmas.

Yes, the Mehdi/Lewin debate was essentially about the setup, not the fundmental physics.

There was no "debate" about the setup. Mehdi simply ignored the previous lecture Lewin gave, where he probed a solenoid with a Hall sensor and showed that probes outside the solenoid would not be affected by the field.

He even gave quantitative figures for the magnetic field in Gauss.

Neither you nor Mehdi conducted such precise measurements, and you like to claim that you are practical engineers. Lewin puts the two of you to shame.

See for yourself @24:13. I recommend you watch the whole lecture though.



Lewin was therefore understandably outraged by Mehdi's accusation of "bad probing" and dismissed Mehdi's claims as bullshit, because that's precisely what they are.

One advice from a fellow engineer: avoid being seen around Mehdi. He is an embarrassment to the whole engineering field. He should renounce his academic title. I myself do not consider him an engineer and do not recommend any of his videos.

But when you introduce a practical engineering question, and not mention any practical engineering ways of looking at it or coming up with the answer, then you invite the lively debate we have seen.

Translation: We, the parcel of engineers who despise Maxwell's equations and the Poynting theorem, self styled "practical engineers", are butthurt because we cannot devise a way to solve a problem proposed by a thought experiment with the limited set of tricks we rely on to get away in our trade.

The solution to this problem is simple: stop despising Maxwell's equations and the Poynting theorem. Those who are really getting closer to understanding how to conduct experiments are "faffing around the edges of physics" and running EM simulations (because a complete analytical solution is probably too complicated).

https://youtu.be/aqBDFO1bEs8
 

Offline Howardlong

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Re: "Veritasium" (YT) - "The Big Misconception About Electricity" ?
« Reply #688 on: December 25, 2021, 10:14:15 am »
But when you introduce a practical engineering question, and not mention any practical engineering ways of looking at it or coming up with the answer, then you invite the lively debate we have seen.

Translation: We, the parcel of engineers who despise Maxwell's equations and the Poynting theorem, self styled "practical engineers", are butthurt because we cannot devise a way to solve a problem proposed by a thought experiment with the limited set of tricks we rely on to get away in our trade.

The solution to this problem is simple: stop despising Maxwell's equations and the Poynting theorem.

Again, you present a straw man, and throw in ad hominem and smears for good measure. You keep trying to support your view with completely disingenuous and hyperbolic misrepresentations of others’ views, and it severely detracts from your own position.
 

Offline adx

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Re: "Veritasium" (YT) - "The Big Misconception About Electricity" ?
« Reply #689 on: December 25, 2021, 01:14:34 pm »
... Lewin puts the two of you to shame. ... ... [there's a whole video in there] ... and dismissed Mehdi's claims as bullshit, because that's precisely what they are.

Would have appreciated a spoiler alert.

Quote from: bsfeechannel
Translation: We, the parcel of engineers who despise Maxwell's equations and the Poynting theorem, self styled "practical engineers", are butthurt because we cannot devise a way to solve a problem proposed by a thought experiment with the limited set of tricks we rely on to get away in our trade.

My point exactly. Re-translation: We, the parcel of engineers who drool over Maxwell's equations and the Poynting theorem, self styled "<TBD> engineers", are butthurt because we cannot devise a way to solve a problem proposed by a thought experiment with the limited set of tricks we rely on to get away in our trade.

No one has come up with a clean solution. Transmission line theorists, antenna masochists, electromagnetic solverists, or wire unreelists for that matter.

I'd better say happy Boxing Day and leave it there for those in timezones who may wish for a day off  :)
 
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Offline adx

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Re: "Veritasium" (YT) - "The Big Misconception About Electricity" ?
« Reply #690 on: December 25, 2021, 02:28:36 pm »
One more.

"Uninformed cretins" can design things using solutions devised by those with the appropriate knowledge. If someone gives you the equations you need to design a transformer, you can do that without knowing Faraday's law. However you would not know exactly why that equation works, whether that is an approximation, or what assumptions were taken, etc. You'd be limited.

When something odd or different from expected happens, you'll be lost.
I think I am somewhat in the "Uninformed cretin" category as I 'use solutions devised by those with the appropriate knowledge'. So far that approach hasn't let me down until this thread. In my Reply #648 I proposed a solution based on what I believe is a reasonable approach. I would appreciate someone looking at this and either verifying my assumptions or shooting them down.

It seems a simple question. A wire carrying current creates a flux. A proportion of that flux cuts a parallel wire. We could put figures on it to match AlphaPhoenix video: wires 1mm diameter, spacing 250mm. What's the proportion?

The trick to being an uninformed cretin is to know enough to ask the right question.

Unless someone can hold my hand (and doesn't mind Excel) that maths is not for me.

I am more in the "informed cretin" category, as I intentionally shun "solutions devised by those with the appropriate knowledge" as the seat of all confusion, then contradictorily jump on the web to find a calculator or the knowledge that is a cache miss.

You make a lot of interesting points, like a description for skin effect behaviour. I just don’t know the answers to a precision necessary to say.

It might be even simpler than your transformer comparison. Consider a balanced transmission line just driven differentially. After the pulse is launched, the wires at the send end will carry an unchanging flux, and an unchanging voltage across the capacitance, so they will have no effect (apart from series resistance). It seems a good conclusion to say that it is only the pulse edge that causes all the effects. If it is a sharp step, then it all happens approximately in a plane, roaring along at the speed of light. Even Excel might struggle in that situation. Like (I think I remember) you say, there's no skin effect, because there is no high frequency content in the return current (it's all DC). Again, that DC arises because a plane of effect is moving away at the speed of light, all the energy goes into adding magnetic and electric field onto the end, it does so using a ~THz radio transmission of the same nature as that which provided the leading edge of the pulse in these experiments. All from the frame of the wire. Things might be different in the frame of plane, and really different when it hits the discontinuity that causes phase and therefore time to invert.

Remember "frequency components" aren't real unless there is actual repetitive motion in the system. It's just a transform. It only works because of linearity, and time invariance.
 

Offline EEVblog

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Re: "Veritasium" (YT) - "The Big Misconception About Electricity" ?
« Reply #691 on: December 25, 2021, 11:59:31 pm »
Like I've said before, if Derek didn't have the question in there, this thead likely wouldn't exist, and there wouldn't be any response videos. Most of us would have just said "cool video on Maxwell and Poynting" and that would be it. But when you introduce a practical engineering question, and not mention any practical engineering ways of looking at it or coming up with the answer, then you invite the lively debate we have seen.
Without being primed on how to react, it seems the world has struggled to come up with an answer.

I don't think so. Every engineer seems to look at this question and come up the C (1s/c) answer using one of several methods that give the same answer.
The only debate is essentially how much it turns on, which is moot, because the question itself ignores that.
 

Offline SandyCox

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Re: "Veritasium" (YT) - "The Big Misconception About Electricity" ?
« Reply #692 on: December 26, 2021, 10:53:15 am »
Quote
The only debate is essentially how much it turns on, which is moot, because the question itself ignores that.
According to maximum power transfer theory, the answer is 25% (of the steady-state power), provided that the resistance of the light bulb is twice the characteristic impedance of the lossless transmission line.
 

Offline adx

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Re: "Veritasium" (YT) - "The Big Misconception About Electricity" ?
« Reply #693 on: December 26, 2021, 01:06:23 pm »
Like I've said before, if Derek didn't have the question in there, this thead likely wouldn't exist, and there wouldn't be any response videos. Most of us would have just said "cool video on Maxwell and Poynting" and that would be it. But when you introduce a practical engineering question, and not mention any practical engineering ways of looking at it or coming up with the answer, then you invite the lively debate we have seen.
Without being primed on how to react, it seems the world has struggled to come up with an answer.

I don't think so. Every engineer seems to look at this question and come up the C (1s/c) answer using one of several methods that give the same answer.
The only debate is essentially how much it turns on, which is moot, because the question itself ignores that.

Actually you're right, some of us are getting quite carried away by the details. The original question is generous perhaps to a fault, because the only sensible response to "switch voltage ... 1m away ... any current ... how long?" is "um, speed of light?".

But it's a tricky layout, so we might wonder if it's a trick question (voltage step applied between A and B, load across C and D);
1/ is it just an insignificant blip? No.
2/ does it turn off again before 1 second? No.
 

Offline SiliconWizard

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Re: "Veritasium" (YT) - "The Big Misconception About Electricity" ?
« Reply #694 on: December 26, 2021, 06:59:21 pm »
Of course the "question" in Veritasium's video is a trick one, and ill-formed in many ways, as we said.
Whether it was fully intentional or not, only he can answer that. But as he's an experienced Youtuber, I'd be willing to bet it was intentional. The "questionable question" and its questionable, or at least partial answer (as is) sure helped make the video viral. There is science, which is always interesting to discuss, and then there is pure marketing. :popcorn:
 
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Offline bsfeechannel

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Re: "Veritasium" (YT) - "The Big Misconception About Electricity" ?
« Reply #695 on: December 27, 2021, 03:15:43 am »
Straw man. No one's discouraging anyone from trying to understand either.

Some of us are just saying that for most EEs, there is no practical need to resort to directly using either.

Yes, we are discouraging people to understand the problem.



Look what Dave said @3:36, after Derek presented the misconception he's talking about.

"Yes... and no. From a physics point of view, yes, it's wrong, from uh field theory point of view yes it... like the electromagnetic field theory point of view, it is wrong. But it's actually nothing wrong with using this kind of example. But in terms of actual practical engineering or... engineers have developed uh lots of tools, methods and laws like Ohm's law, Kirchhoff's laws, maximum power transfer, theories, transmission line theory, signal theory, all sorts of theorems we developed to give a more practical insight rather than what is actually happening at the physics level."



Australian is not my first language and I may be getting deaf with age, but did I hear that engineers developed the Ohm's law? Wasn't Georg Ohm a PHYSICIST? Wasn't Gustav Kirchhoff also a PHYSICIST?

The maximum power theorem was published by Moritz von Jacobi. The transmission line theory was developed by Lord Kelvin and Oliver Heaviside based on the work of James Maxwell, a PHYSICIST. Those were engineers, but also PHYSICISTS, big ones, by the way, proving there's no such thing as a "practical insight" as opposed to the "physical level".

The full-fledged engineer is someone with a practical approach AND a "physics level" insight.

This dichotomy Dave proposed is a false dilemma: that's the real fallacy here.

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I know you enjoy using them as tools to make you classes more challenging, and good for you.

I don't teach EE. You must be mistaking me for someone else.

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But for the vast majority of EEs, that is all they will ever be: a challenging class exercise.

The "vast majority", the "practical engineering", the "engineering 101", the "Derek's trolling", the "trick question". All of these are strawmen. They are irrational arguments that don't answer the question: how long does it take for the energy coming out of the battery to first arrive at the lamp after the switch is closed?
 

Offline bdunham7

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Re: "Veritasium" (YT) - "The Big Misconception About Electricity" ?
« Reply #696 on: December 27, 2021, 03:56:19 am »
the question: how long does it take for the energy coming out of the battery to first arrive at the lamp after the switch is closed?

 :horse: :horse: :horse: :horse: :horse:

Actually you mean " the question: how long does it take for some of the energy (meaning any discernable--or even not discernable according to some--amount) coming out of the battery to first arrive at the lamp after the switch is closed?"

And the only real dispute there is about the definition of 'how long' in the context of the concepts of simultaneity and observability when relativistic speeds are involved.  Not that I see any need to beat that horse corpse either.
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 
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Offline bsfeechannel

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Re: "Veritasium" (YT) - "The Big Misconception About Electricity" ?
« Reply #697 on: December 27, 2021, 04:48:10 am »
My point exactly. Re-translation: We, the parcel of engineers who drool over Maxwell's equations and the Poynting theorem, self styled "<TBD> engineers", are butthurt because we cannot devise a way to solve a problem proposed by a thought experiment with the limited set of tricks we rely on to get away in our trade.

Nah, we're not drooling. We are just saying: shut up bitches! Engineering is not the harbor of ignorance. You see, in the past, engineers had insights in physics, that's why many of them contributed both to engineering and science. Now engineers are seen as dogmatic people who cannot think outside of the box. People you have to be careful not to trigger when you want to expose something that go against their preconceptions.

Talking about fields, Maxwell and Poynting is OK. Posing a question about a ridiculous circuit that challenge the understanding of engineers is stepping into a "forbidden" territory. These engineers think they "own" circuit theory. They don't understand that circuit theory is just as physics as the Maxwell equations are. In fact circuit theory is just a special case of them.

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No one has come up with a clean solution. Transmission line theorists, antenna masochists, electromagnetic solverists, or wire unreelists for that matter.

The solution was given by Derek. You have a Poynting vector pointing directly from the battery to the load. The electromagnetic field propagates at the speed of light, so energy will first arrive at the load at exactly 1 m/c seconds. That's simple and elegant. AND there's no other "approach" to the problem. Other "approaches" will give you the wrong answer.
 

Offline adx

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Re: "Veritasium" (YT) - "The Big Misconception About Electricity" ?
« Reply #698 on: December 27, 2021, 11:30:42 am »
But still, you'd think one camp would win out over the other with a technically superior result given all the advances of humanity and technology, but it just hasn't happened.

Because that's just not how science works. There is no "truth" that wins. There are just human-made models that fit reality through experiments under certain conditions. Of course models that make no sense and don't pass the test of reproducible experiments are just garbage to throw away. For the rest, it's all relative. As Einstein would say. In other words, we can prove some theories are patently wrong (it just takes one counter-example), but we can't prove anything is "true". We can just have a good level of confidence that we've not been able to prove it wrong so far, and that it appears useful when applied to *some* reality.

I know. But in this case, the science is a religion - well accepted, rarely questioned, and it should be expected to work for the purpose it was designed. People are resorting to science the method, because they are confused over science the consensus. As it should be in my mind, but in this case I don't believe there is anything fundamentally wrong with the consensus, if one were to exist. There are books of truth, but they are designed to guide the thinking of the faithful, rather than provide a result. The real power is held by those high in the system - the corporate heads of places like Cadence. Even then, they are only responding to some market reality, itself an invented one.

People are running around testing things like it's 1900. It's a bit of a tricky question, but not complex and not beyond human knowledge.

The question itself is ill-defined to begin with, which is the main reason for so much debate and people trying to prove things through experiments (most of them having no clue how to conduct those experiments properly, by the way, IMHO.) As I (and others) have said a while ago now, what IS the real question here? Can you state it clearly, and if so, how do the various experiments we have seen so far answer the question exactly? Why is it that people confuse steady-state and transient behavior?

That said, it shows that modeling power transfer using lumped models, while certainly possible, can be pretty tricky. And yes, it's related to the whole previous "Lewin" debate. In the end, some have tried to show that using lumped models was just not possible in some cases, some have tried to prove the opposite. Where is the "truth" that many of us are so eager for? "The truth is out there", as they say. ;D
...

I'm not so sure about it being ill-defined, or a trick question, especially now. Well-meaning trolling, clickbaitey cage-rattling and gentle handwaving aside, I think the direct answer is trivial, as I've since posted (above, with question being "switch voltage ... 1m away ... any current ... how long?"). It's even given to us, twice (once as a multiguess hint, and then the answer in the video). But a solution to the core of the details laid out for the 'problem', so we can see plots, has so far evaded everyone. Transmission lines don't account for radiation, no one has ever made an antenna that long, and it seems to be too out of this world for both numerical solvers and analytical thinkers to actually do to a "this is the solution give or take not many %" level.
 

Offline SiliconWizard

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Re: "Veritasium" (YT) - "The Big Misconception About Electricity" ?
« Reply #699 on: December 27, 2021, 10:38:05 pm »
the question: how long does it take for the energy coming out of the battery to first arrive at the lamp after the switch is closed?

 :horse: :horse: :horse: :horse: :horse:

Actually you mean " the question: how long does it take for some of the energy (meaning any discernable--or even not discernable according to some--amount) coming out of the battery to first arrive at the lamp after the switch is closed?"

And the only real dispute there is about the definition of 'how long' in the context of the concepts of simultaneity and observability when relativistic speeds are involved.  Not that I see any need to beat that horse corpse either.

Yep. Agreed, and precisely.
 


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