I thought this was interesting. I think it hints at reasons why certain grounding schemes don't work as well as others.
https://youtu.be/2AXv49dDQJw?si=Obj27QA5Ov_AhBeU
Interesting video on current flow
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Fischerman
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Interesting video on current flow
Early brewers were primarily women, mostly because it was deemed a woman's job. Mesopotamian men, of some 3,800 years ago, were obviously complete assclowns and had yet to realize the pleasure of brewing beer.
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Stevem
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Re: Interesting video on current flow
That video was incredible and also reminded me that when batteries and electronics where first developed it was thought that DC current flowed from a positively charged node to a negative which it was later found it did not.
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
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WhopperPlate
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statorvane
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Re: Interesting video on current flow
Very cool video. I know what he means by o-scopes being limited.
This would make a good topic for a Masters thesis.
This would make a good topic for a Masters thesis.
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martin manning
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Re: Interesting video on current flow
But really just a nice demonstration of transmission line behavior and a hydraulic analog.
Re: Interesting video on current flow
That's an amazing experimental setup for sure, and the video was really entertaining. However, it's educational value feels dubious at best for at least a couple pretty significant reasons. I'm not a college professor, and I'm not really sure what level of competence to expect from people with only a few years of experience working with electrons. I'm not going to give him a letter grade for this presentation, but I will go as far as saying that if I were grading this as a Physics project I would give him a better grade than if it were an Electrical Engineering project.
I don't know how much of his planning and analysis was omitted to cut the length of the video down to less than 30 minutes, so he might possibly have actually paid attention to these details that I find lacking in the video. The omissions might possibly be just to "dumb things down" for the youtube audience, and not for an audience of people with knowledge and experience. But based purely on what was included in the video and without making any assumptions about what might or might not have been cut out in the editing, I see a few fundamental errors and deficiencies that simply don't stand up to peer review.
The demonstration uses three sections of 23 meters of twisted pair cable, which is a total of either 69 or 138 meters of cable. He didn't say whether the 23 meters per section was the total length of the twisted pair, or the length of each half of the twisted pair. The wire doesn't have a large resistance, but it's not zero in EE theory. Back of the envelope math for the sake of getting started and moving forward? First pass or rough draft planning? Sure, go ahead and call the wire 0 ohms for now while you're setting things up and worry about fine tuning the details later on down the road. Experimental measurements on the scale of the speed of light and the distance moved by the participating electrons? No, the wire is not 0 ohms.
I'm not going to dig through the video again for the exact quote, but he did mention, once, offhandedly, something to the effect that he had only learned about inductance in transmission lines for the first time during the setup for this experiment. This is a giant red flag. He didn't mention the capacitance of the twisted pair at any point in the description of his setup. This is another giant red flag. He built a resonant circuit with R L and C components, hooked it up to an o-scope in a way that displays the resonant frequency of the circuit in quantitative numbers, and yet he doesn't even seem to know what a capacitor is or why the capacitance of either 69 or 138 meters of cable might matter. https://www.youtube.com/watch?v=2AXv49dDQJw&t=464s At this timestamp in the video he starts explaining how he doesn't understand the behavior of the circuit and 40 seconds later, he says that the voltage in the circuit spikes up when the battery is connected and then "mystery stuff happens in the rest of the circuit". What's happening isn't mysterious at all. Ask the venerable guru, Eli the ice man, what he thinks is happening and he'll catch you up to speed on the EE 101 lesson for those couple days of class you missed. Or maybe if you're not interested in the theory and you just want to make a measurement, go to amazon.com and pick up a https://en.wikipedia.org/wiki/Time-domain_reflectometer for $100.
He mentions electrons bunching up at the higher voltages, and this is fundamentally incorrect from a Physics 101 point of view. Electrons at 0 VDC are abundant, and in relative terms a voltage higher than X VDC is a deficiency of electrons. So when he's describing the actions of the electrons (bunching up) in the circuit, he has things entirely backwards. This could be embarrassing for him, but the fundamentally incorrect theory of "conventional current" is still widely taught and learned and to be fair it doesn't usually make any practical difference at all. However, this is a video attempting to describe what electrons "do", and he got that part wrong. Shame on his teachers, if anyone.
I stopped watching about 15 minutes in, maybe there's more interesting parts in the end of the video but my first impression is that video probably peaks around the 11 minute mark and probably goes downhill from there.
But even after all of those errors, I really do appreciate the work he put into setting up the experiment where he measured the voltage at a couple dozen points and turned the voltages into a really nice looking display of how the field propagates along the wires over time. That visualization and the thought process that led him to get to that point of (not quite fully) understanding what's happening is something that is admirable and I'm pretty sure he'd be able to make a much more correct and accurate video if he took the time to do a little bit more homework first.
I don't know how much of his planning and analysis was omitted to cut the length of the video down to less than 30 minutes, so he might possibly have actually paid attention to these details that I find lacking in the video. The omissions might possibly be just to "dumb things down" for the youtube audience, and not for an audience of people with knowledge and experience. But based purely on what was included in the video and without making any assumptions about what might or might not have been cut out in the editing, I see a few fundamental errors and deficiencies that simply don't stand up to peer review.
The demonstration uses three sections of 23 meters of twisted pair cable, which is a total of either 69 or 138 meters of cable. He didn't say whether the 23 meters per section was the total length of the twisted pair, or the length of each half of the twisted pair. The wire doesn't have a large resistance, but it's not zero in EE theory. Back of the envelope math for the sake of getting started and moving forward? First pass or rough draft planning? Sure, go ahead and call the wire 0 ohms for now while you're setting things up and worry about fine tuning the details later on down the road. Experimental measurements on the scale of the speed of light and the distance moved by the participating electrons? No, the wire is not 0 ohms.
I'm not going to dig through the video again for the exact quote, but he did mention, once, offhandedly, something to the effect that he had only learned about inductance in transmission lines for the first time during the setup for this experiment. This is a giant red flag. He didn't mention the capacitance of the twisted pair at any point in the description of his setup. This is another giant red flag. He built a resonant circuit with R L and C components, hooked it up to an o-scope in a way that displays the resonant frequency of the circuit in quantitative numbers, and yet he doesn't even seem to know what a capacitor is or why the capacitance of either 69 or 138 meters of cable might matter. https://www.youtube.com/watch?v=2AXv49dDQJw&t=464s At this timestamp in the video he starts explaining how he doesn't understand the behavior of the circuit and 40 seconds later, he says that the voltage in the circuit spikes up when the battery is connected and then "mystery stuff happens in the rest of the circuit". What's happening isn't mysterious at all. Ask the venerable guru, Eli the ice man, what he thinks is happening and he'll catch you up to speed on the EE 101 lesson for those couple days of class you missed. Or maybe if you're not interested in the theory and you just want to make a measurement, go to amazon.com and pick up a https://en.wikipedia.org/wiki/Time-domain_reflectometer for $100.
He mentions electrons bunching up at the higher voltages, and this is fundamentally incorrect from a Physics 101 point of view. Electrons at 0 VDC are abundant, and in relative terms a voltage higher than X VDC is a deficiency of electrons. So when he's describing the actions of the electrons (bunching up) in the circuit, he has things entirely backwards. This could be embarrassing for him, but the fundamentally incorrect theory of "conventional current" is still widely taught and learned and to be fair it doesn't usually make any practical difference at all. However, this is a video attempting to describe what electrons "do", and he got that part wrong. Shame on his teachers, if anyone.
I stopped watching about 15 minutes in, maybe there's more interesting parts in the end of the video but my first impression is that video probably peaks around the 11 minute mark and probably goes downhill from there.
But even after all of those errors, I really do appreciate the work he put into setting up the experiment where he measured the voltage at a couple dozen points and turned the voltages into a really nice looking display of how the field propagates along the wires over time. That visualization and the thought process that led him to get to that point of (not quite fully) understanding what's happening is something that is admirable and I'm pretty sure he'd be able to make a much more correct and accurate video if he took the time to do a little bit more homework first.
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Fischerman
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Re: Interesting video on current flow
I stopped reading as soon as you wrote this. At least watch the whole thing before you shoot holes in it. It sort of invalidates your whole post.I stopped watching about 15 minutes in, maybe there's more interesting parts in the end of the video…
Early brewers were primarily women, mostly because it was deemed a woman's job. Mesopotamian men, of some 3,800 years ago, were obviously complete assclowns and had yet to realize the pleasure of brewing beer.
Re: Interesting video on current flow
No, it doesn't. I stopped watching because he had started explaining things in a way that is absolutely incorrect because his foundation he had been building on for the previous 15 minutes is full of ignorance of basic fundamental facts. He needs to go back to square one and re-evaluate the whole circuit with the understanding that wires have inductance, capacitance, and resistance. His circuit is more complicated than he understands, and his conclusion is a swing and a miss because of it.