Earlier quoted context omitted.
In my opinion the video made a couple of mistakes, which I think ElectroBoom's response* addresses nicely. Also its proof using the pointing vector to show the flow of energy is misleading; In the video Derek shows that the energy flows toward the lamp when the circuit is already in a stable configuration, but the point of the video is to explore what happens before the circuit reaches that configuration. This is rel…
I thought it was the Poynting vector? Easy to remember because it points in the direction of power flow :)
I bought 1000 meters of wire to settle a physics debate [video]
141–150 of 242 posts
Re: I bought 1000 meters of wire to settle a physics debate [video]
#142Earlier quoted context omitted.
Most people didn't have EE education at college level. Transmission line or radio wave carrying energy is a concept usually taught much later in ones schooling. Derek basically want to target mass market that receive basic electrical knowledge that actively tells you electric "only" flows in cable. A lot of people replying to his video subsequently demonstrate that Derek is right that these group of people have the n…
>people have the not exactly right idea taught at school could it not also be that some of these students didn't actually learn what was being taught, and just squeaked by with minimum grades to not have to take it again?
Re: I bought 1000 meters of wire to settle a physics debate [video]
#143So, I genuinely do not get the "controversy" over the Veritasium video. AFAIU, the entire point of the video was to show that electricity travels not through wires but via electric fields ("through the air" so to speak). To illustrate this, he sets up an experiment with parameters such that the conclusion can only mean that some electricity has traveled to the bulb before any could arrive through/around the wires. He…
At first order the bulk of the energy follow the wire like a train on its rails.
Sure you could put a windmill turbine one meter next to the train and the wind from the train passing will make it turn immediately, but no one would argue about that the wind carry most of the energy.
It works this way because the electrons are stuck on the wire like a train is stuck on its rails. The Electro-Magnetic field on the other hand like the wind is free to permeate space. What is important to understand is that electrons and EM-field are two-distinct things that are coupled together.
Derek's video tried to explain transmission line theory, but didn't do the experiment while making grandiose claims about a fictional setup. Kudos to alpha phoenix for doing the experiment.
Given that Derek recently created multiple "debate" videos, and that he is more interested in the way to teach Science and how to reach a lot of people than by Science itself, it feels like he probably has engineered this controversy himself for views as a meta-experiment.
A lot of video responses from unknown youtubers show a better understanding than the original. For example you can see a numerical simulation of the electro magnetic fields (with Ansys) https://youtu.be/aqBDFO1bEs8?t=364 that show how electricity move (the separation distance between the wire there is only a few centimeters).
The problem though is interesting if you try to understand how exactly the energy transfer is happening : Is it capacitive coupling, Is it inductive coupling, Is it EM radiation ? Which one exactly is the dominant term ? Where exactly are the electrons ? How are the electrons interacting with the field ? How can you shield it to isolate and show the various effects (magnetic shielding, electrical shielding) ?
Re: I bought 1000 meters of wire to settle a physics debate [video]
#144Earlier quoted context omitted.
Bring any topic however widely known and thoroughly proven to a large enough general audience and you will always find people with no actual knowledge that will question it. Try to find a post on HN with a lot of upvotes and comments where everybody would agree on something. If you want to know if there is "physics debate" ask people who know physics, not commenters on Youtube or HN.
Why are random commenters not allowed to have a debate regarding physics?
However, saying the phrase "a debate" -usually- leads people to believe there exists a debate about in the field of between experts who study .
Re: I bought 1000 meters of wire to settle a physics debate [video]
#145So, I genuinely do not get the "controversy" over the Veritasium video. AFAIU, the entire point of the video was to show that electricity travels not through wires but via electric fields ("through the air" so to speak). To illustrate this, he sets up an experiment with parameters such that the conclusion can only mean that some electricity has traveled to the bulb before any could arrive through/around the wires. He…
Nothing (except forgetting the units of meters) he said is wrong. It's just a bit uncharacteristic that the video didn't match the initial quiz, and it ignores some of the most interesting bits of the behavior. But it wasn't targeted at EEs who are already familiar with the "simple" transmission line behavior, it was targeted at people who haven't ever learned or dealt with that. So the steady-state behavior would have distracted from the focus of the video IMO.
Re: I bought 1000 meters of wire to settle a physics debate [video]
#146Earlier quoted context omitted.
His technical errors include the “correct” multiple-choice answer being that the time to turn on is “1/c s”. That evaluates to 3.3e-9 s^2/m. It’s not even a time. Failing basic dimensional analysis is grossly sloppy.
It should be obvious that the "c" here was used as a magnitude not with units. Saying that's "failing dimensional analysis" is in itself grossly sloppy - since it totally misses the context.
Re: I bought 1000 meters of wire to settle a physics debate [video]
#147Earlier quoted context omitted.
I would echo this sentiment. Did this video not confirm exactly what Veritasium claimed (the small but noticeable "instantaneous" i.e. 1/c current)?
I think the confusion is that Veratisium's original video made it seem like this was the only/main way electricity travels, whereas in reality, there's two separate ways: One of them take's 1/c and the other takes c/2. Also, what most people think of the light bulb going on in the real world would be the c/2 one, not the 1/c one.
1/c was because the distance between the lightbulb and the battery was 1 meter. m / m/s = s
With c as the numerator, I don't even know what the units of that 2 would be? m/s²?
Re: I bought 1000 meters of wire to settle a physics debate [video]
#148Earlier quoted context omitted.
I would echo this sentiment. Did this video not confirm exactly what Veritasium claimed (the small but noticeable "instantaneous" i.e. 1/c current)?
The controversy is that it twists the standard definition of "on": the video boldly asserts its shocking answer of 1/d at first, only later to admit (with very little clarity) that the 1/d answer is only true if your definition of "on" is a small electromagnetic spike. This also means that the "misconception" claim is really just click-bait and really there was never any misconception.
Re: I bought 1000 meters of wire to settle a physics debate [video]
#149So, I genuinely do not get the "controversy" over the Veritasium video. AFAIU, the entire point of the video was to show that electricity travels not through wires but via electric fields ("through the air" so to speak). To illustrate this, he sets up an experiment with parameters such that the conclusion can only mean that some electricity has traveled to the bulb before any could arrive through/around the wires. He…
I love his videos, but the reason most people are missing the point is because he only obliquely hits the point. The title and thumb are the clickbaitiest he's ever done, and the content does a wide end-run around the facts, rather than tackling them head on. This is also why there are so many rebuttal videos that agree with him and explain it more clearly: he failed to clearly state his argument/explanation. The circumlocutious explanation does little to edify the audience or clarify the concept.
Re: I bought 1000 meters of wire to settle a physics debate [video]
#150Earlier quoted context omitted.
>people have the not exactly right idea taught at school could it not also be that some of these students didn't actually learn what was being taught, and just squeaked by with minimum grades to not have to take it again?
fwiw, I definitely was given the wires and electrons are like a pipe for water somewhere during schooling, and it was interesting to hear a deeper explanation.
To the point, during the time that I was learning fields produced around a wire carrying a current, I was also learning recording studio audio and how hums can be created by running cables in parallel and avoided by crossing them perpendicularly. I had a conversation about it with said physics teacher, and he gave a lecture about it the next day. Yeah, one of those teachers that sets one on a positive course.