4 ms·

One thing about Veritasium is that they do get things wrong. They did one on electric circuits where if you had a circuit that was miles long with the energy so

One thing about Veritasium is that they do get things wrong. They did one on electric circuits where if you had a circuit that was miles long with the energy source sitting right next to you, you would get current as soon as you turned on the electrical circuit because 'electricity doesnt follow the wire' or something along those lines. This has been disproven by people doing experiments

etskinner 5y ago
Can you share the experiments that disprove it? The one video I saw proved it. Someone set up some long wires over a farm field, and measured the time to first current flow, which was faster than if the current had to travel the whole wire length. Granted, the full current flow doesn't appear until later, but the first little bit of current is there, which is exactly what Derek said in the Veritasium video
- autokad 5y ago
  I believe this is the same video, the author theorized (probably correctly) that it was because there was residual 'power' on the wire, as it acts like a giant capacitor, among other things. this is because the wire that immediately showed up was extremely small and dissipated very quickly. https://www.youtube.com/watch?v=2Vrhk5OjBP8 https://www.youtube.com/watch?v=2Vrhk5OjBP8
mannykannot 5y ago
One could quibble over the details of the experiment, such as what sort of lamp to use, but Maxwell's laws would have to be repealed for the experiment to not work essentially as Veritasium claimed. Check out "electromagnetic induction" and "displacement current".
- LordDragonfang 5y ago
  The problem is that he frames the whole whole experiment as if the inductive current is a property of the circuit rather than a property of two separate wires being next to each other - he heavily implies the inductance is result of the current "starting" to travel through the loop, and IIRC never once uses the term "inductance" (which seems odd for a video purporting to promote understanding rather than just be clickbait). (The fact that the loop is closed can't be relevant by simple thought experiment, because otherwise it implies you could get ftl signaling by having a switch on the physically distant checking whether the "tiny current" flows when you close the source)
  - mannykannot 5y ago
    Veritasium may not have mentioned either inductance or displacement current; I don't recall. He did, however, talk about an even more abstract concept which subsumes the effect of both: the Poynting vector. Pedagogically speaking, it was probably a mistake to go there without covering the prerequisites in considerable detail, but that does not, IMHO, make it clickbait: for someone who has some background, this could be food for thought. Whether the distant end of the loop is closed or not makes a difference eventually, where 'eventually' means once the initial EM wave has reflected from the end and returned to the load.
    - LordDragonfang 5y ago
      > Pedagogically speaking, it was probably a mistake to go there without covering the prerequisites And considering the fact that Derek has a Ph.D. in physics education research [1] that seems like an odd mistake for him to make, unless it was intentional. As another commenter pointed out [2] Derek's content lately seems to be tailored to the maxim of "Make people believe they're thinking and they'll love you. Make them actually think, and they will hate you." It seems intended to invoke incredulity rather than understanding, presumably because he's decided the former is more marketable - because providing incomplete understanding and phrasing things in a way that's just technically correct enough to invite flame wars boosts engagement and therefore virality. Yet another commenter [3] invoked https://xkcd.com/169/ https://xkcd.com/169/, which I think is apt. [1] https://en.wikipedia.org/wiki/Derek_Muller#Early_life_and_education https://en.wikipedia.org/wiki/Derek_Muller#Early_life_and_ed... [2] https://news.ycombinator.com/item?id=30558859 https://news.ycombinator.com/item?id=30558859 [3] https://news.ycombinator.com/item?id=30559815 https://news.ycombinator.com/item?id=30559815
      - deleted 5y ago
        [deleted]
      - mannykannot 5y ago
        You appear to have seen way more of Veritasium's videos than I have, which seems rather odd, given that you dislike them so much.
gaze 5y ago
No, you’re wrong. If you hook an ohmmeter to a 10 light-second long piece of LOSSLESS coax, you’ll measure the characteristic impedance (50 or 75 ohms, probably) of the cable for 20 seconds. I have done this personally with shorter coax and TDR.

etskinner 5y ago

Can you share the experiments that disprove it? The one video I saw proved it. Someone set up some long wires over a farm field, and measured the time to first current flow, which was faster than if the current had to travel the whole wire length. Granted, the full current flow doesn't appear until later, but the first little bit of current is there, which is exactly what Derek said in the Veritasium video

autokad 5y ago
I believe this is the same video, the author theorized (probably correctly) that it was because there was residual 'power' on the wire, as it acts like a giant capacitor, among other things. this is because the wire that immediately showed up was extremely small and dissipated very quickly. https://www.youtube.com/watch?v=2Vrhk5OjBP8 https://www.youtube.com/watch?v=2Vrhk5OjBP8

mannykannot 5y ago

One could quibble over the details of the experiment, such as what sort of lamp to use, but Maxwell's laws would have to be repealed for the experiment to not work essentially as Veritasium claimed. Check out "electromagnetic induction" and "displacement current".

LordDragonfang 5y ago
The problem is that he frames the whole whole experiment as if the inductive current is a property of the circuit rather than a property of two separate wires being next to each other - he heavily implies the inductance is result of the current "starting" to travel through the loop, and IIRC never once uses the term "inductance" (which seems odd for a video purporting to promote understanding rather than just be clickbait). (The fact that the loop is closed can't be relevant by simple thought experiment, because otherwise it implies you could get ftl signaling by having a switch on the physically distant checking whether the "tiny current" flows when you close the source)
- mannykannot 5y ago
  Veritasium may not have mentioned either inductance or displacement current; I don't recall. He did, however, talk about an even more abstract concept which subsumes the effect of both: the Poynting vector. Pedagogically speaking, it was probably a mistake to go there without covering the prerequisites in considerable detail, but that does not, IMHO, make it clickbait: for someone who has some background, this could be food for thought. Whether the distant end of the loop is closed or not makes a difference eventually, where 'eventually' means once the initial EM wave has reflected from the end and returned to the load.
  - LordDragonfang 5y ago
    > Pedagogically speaking, it was probably a mistake to go there without covering the prerequisites And considering the fact that Derek has a Ph.D. in physics education research [1] that seems like an odd mistake for him to make, unless it was intentional. As another commenter pointed out [2] Derek's content lately seems to be tailored to the maxim of "Make people believe they're thinking and they'll love you. Make them actually think, and they will hate you." It seems intended to invoke incredulity rather than understanding, presumably because he's decided the former is more marketable - because providing incomplete understanding and phrasing things in a way that's just technically correct enough to invite flame wars boosts engagement and therefore virality. Yet another commenter [3] invoked https://xkcd.com/169/ https://xkcd.com/169/, which I think is apt. [1] https://en.wikipedia.org/wiki/Derek_Muller#Early_life_and_education https://en.wikipedia.org/wiki/Derek_Muller#Early_life_and_ed... [2] https://news.ycombinator.com/item?id=30558859 https://news.ycombinator.com/item?id=30558859 [3] https://news.ycombinator.com/item?id=30559815 https://news.ycombinator.com/item?id=30559815
    - deleted 5y ago
      [deleted]
    - mannykannot 5y ago
      You appear to have seen way more of Veritasium's videos than I have, which seems rather odd, given that you dislike them so much.

gaze 5y ago

No, you’re wrong. If you hook an ohmmeter to a 10 light-second long piece of LOSSLESS coax, you’ll measure the characteristic impedance (50 or 75 ohms, probably) of the cable for 20 seconds. I have done this personally with shorter coax and TDR.