How Electricity Actually Works
This video is sponsored by Brilliant. The first 200 people to sign up via https://brilliant.org/veritasium get 20% off a yearly subscription.
Special thanks to:
Bruce Sherwood, Ruth Chabay, Aaron Titus, and Steve Spicklemore
VPython simulation: http://tinyurl.com/SurfaceCharge
Richard Abbott from Caltech
Electrical Engineering YouTubers:
Electroboom: https://www.youtube.com/c/Electroboom
Alpha Phoenix: https://www.youtube.com/c/AlphaPhoenixChannel
eevblog: https://www.youtube.com/c/EevblogDave
Ben Watson: https://www.youtube.com/channel/UCgZUVIEtBnnBpFWJuxl_E5g
Big Clive: https://www.youtube.com/c/Bigclive
Z Y: https://www.youtube.com/user/ZongyiYang
Further analysis of the large circuit is available here: https://ve42.co/bigcircuit
Special thanks to Dr Geraint Lewis for bringing up this question in the first place and discussing it with us. Check out his and Dr Chris Ferrie’s new book here: https://ve42.co/Universe2021
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References:
A great video about the Poynting vector by the Science Asylum: https://youtu.be/C7tQJ42nGno
Sefton, I. M. (2002). Understanding electricity and circuits: What the text books don’t tell you. In Science Teachers’ Workshop. — https://ve42.co/Sefton
Feynman, R. P., Leighton, R. B., & Sands, M. (1965). The feynman lectures on physics; vol. Ii, chapter 27. American Journal of Physics, 33(9), 750-752. — https://ve42.co/Feynman27
Hunt, B. J. (2005). The Maxwellians. Cornell University Press.
Müller, R. (2012). A semiquantitative treatment of surface charges in DC circuits. American Journal of Physics, 80(9), 782-788. — https://ve42.co/Muller2012
Galili, I., & Goihbarg, E. (2005). Energy transfer in electrical circuits: A qualitative account. American journal of physics, 73(2), 141-144. — https://ve42.co/Galili2004
Deno, D. W. (1976). Transmission line fields. IEEE Transactions on Power Apparatus and Systems, 95(5), 1600-1611. — https://ve42.co/Deno76
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Written by Derek Muller
Edited by Derek Muller
Filmed by Trenton Oliver and Petr Lebedev
Animation by Mike Radjabov and Ivy Tello
Additional video/photos supplied by Getty Images
Music from Epidemic Sound and Jonny Hyman
Produced by Derek Muller, Petr Lebedev, and Emily Zhang
Fantastic revisit! The animations and the simulations were spot-on, and great at showing the difference between the transient “first-second” effect, and the steady-state “rest of time” behavior. The whole “expanding loop of current” thing is a great way to phrase it, because after that poynting loop expands to match the actual physical loop of wire, then stuff starts to behave normally and all of the power is transmitted around the loop very close to the wire.
I still hold that for this simple circuit, turning on a lightbulb with wires much smaller around than they are long, the effect of surface charge vs internal charge is negligible, so you can ignore any skin-effect stuff and say that “mobile” electrons are indeed pushing on other “mobile” electrons using their fields, but I totally agree that that’s a simplification, just a simplification that makes the intuition a lot easier.
I also need to do some math about how far the average “electron” is displaced in order to build the initial charge distribution around some typical circuit elements – axial flow is the only way I understand those charge distributions getting built, and this whole endeavor has made me think hard about what that means. Someday when I think I understand it better I’ll edit up my pt.2 response video – thanks for the shoutout! I’ve got a great experiment in the works to show the “expanding poynting loop” 😁
Proud of you Alpha Phoenix!!
You deserve all the credit he gave you, and so much more.
Your channel is in my top 5, right up there with SmarterEveryday & StuffMadeHere.
Saw your video too, definitely one of the best responses to the original video.
Yo boyyy ! For some reason I feel proud when you got a mention. Keep up the great work ! Congrats
Go Robodogs 😛
You did it first
Well done. You explained your point much better and it fits. The only thing still missing in this video (and the last) is the difference between AC and your battery example. Switching currents in a DC circuit acts very similar to AC but just putting a battery in there and not addressing it can also cause confusion.
I’d also like to see your outdoor experiment move the switch and show a different result as you stated. I doubt you will see a time delay difference in the initial voltage spike.
And a version where one end of the wire is broken.
I mean, by simulating the EM field propagation in the switch you do consider AC because that literally is what AC means? So he did include it IMO
oh moving the switch would be an awesome experiment
Why didn’t I think of that?😄
What an interesting video. As a high Voltage linemen I have experience this field while working under transmission lines. We measured voltage on our truck of 275 volts measured truck to dirt. We could also take light bulbs and light them up while connected to nothing, just under the lines. Really cool stuff. Still a bit hard to wrap ones head around, but i think you did a great job
@gvc jbf wtf dude xD
@gvc jbf x-points allow for faster than liGht travel…
@MegaTurtle95 LMAO yes, no then the comment is not for you you would be surprised how much capital Gs bother ppl to actually Go out of their way to talk ish about it, it Gets aGGravatinG how much the way a stranGer types their words bothers ppl BC they have nothinG better to do I’m here for information not to educate ppl to how we live where I’m from and mind ya beeswax 😂😂😂 BTW awesome name…I like turtles 🐢🐢🐢
@gvc jbf No. Even in this experiment, the information (electrical field, in this case) isn’t travelling faster than C. It is just taking a short-cut through the air-gap directly from the switch to the bulb, rather than going the long way around the wire. But even across the air-gap it is still travelling at light-speed. The air-gap is just a lot shorter distance to travel than around the wire loop, so it gets there more quickly than most people would expect (based on their incorrect assumption that the field is travelling inside the wire).
What I love about this is that this is truly an application of the scientific method within the scientific community. One person (or group) makes an experiment and hypothesis, peers challenge/prove/disprove the original hypothesis, and experiment with their own experiments, explanations, and hypotheses, and then communicate back to the scientific community. This results in further testable hypotheses and finally consensus. Those that question science sometime feel that science is a collection of edicts set in stone foisted upon them by the elite, but science is beautiful because it demands challenge for it work!
I wish I were a writer to explain my thoughts better, but this video and situation surrounding it were simply too inspiring not to comment on.
You nailed it. I don’t think it could be said better really, just with different words.
I think it’s more like Cunningham’s Law. He found out he was wrong about electricity, spent maybe a couple hours researching poynting vectors, and then threw together a video full of holes to get everybody else to explain it instead. And then titled it to sound like we’re going to find out something new about electricity instead of something we learned in high school.
Well said sir, our young protagonist should not apologize for his first video. He galvanized a whole community. Sorry no pun intended.
YouTube appears to be where science can actually happen, rather than the politico corporate crap touted in the old school
Exactly my toughts!
What a great way to show the scientific method!
🤯 Amazing work, Derek! Thank you!
This was a greatly detailed video and I think we are pretty much on the same page! Thanks for the shoutout and going through the trouble of clarification.
P.S. by the way, the resistor in your experiment didn’t quite match the lien impedance, other you would get half your supply voltage right away. But I mean with such small capacitance and inductances, the probing itself could d have added some parasitic components to the lines.
PPS: Like I said above “pretty much on the same page”! It is a complex subject, and I think some nuances could have been addressed better. Maybe Derek and I could sit together and react to nuances to clarify things!
Is anyone able to NOT read this in booms voice?
@Checed Rodgers I’m just happy i was proven right that he was wrong, just integrate along the wire, and he still didn’t address that the light will be always on, even without a battery present, since the special bulb will light by any current, making it actually perfectly zero seconds to light in any setup, we (after all) are talking about a poorly defined thought experiment.
One quibble with the new video that I have….If you look at 20:22 the yellow line goes to five volts before shooting up to the normal voltage when the voltage makes the loop through the wire. You can gauge how long it took for the electricity to travel the complete circuit by looking at how long the yellow line is at 5volts. From this information it looks to me to be visually that the wind up period to achieve 5volts is fairly large and larger than the 1m/c (?) answer that Derick gave. Very interesting videos thanks!
@Veritasium I’d like to point out that there’s never an electric field inside the conductors. If there was waveguides wouldn’t work and you won’t be able to solve Maxwell’s equations at boundaries
Please make this video! Are you going to shock him like you did Linus?
I wanted to say that as a viewer I really appreciate how you went about making this revisit.
It can often be too easy to defend one’s position in a way that is basically just lashing out. Instead this was well put together and explanative
Yes! Now this makes sense. I remember taking distributed parameters systems (transmission lines) in college, but we always assumed the transmission line was the shortest possible path bewtween the source and the load. (This is a perfectly reasonable assumption for a power system because your average 220kV transmission line costs $1Million per mile). This is a neat thought experiment that is important because it challenges fundamental understanding. A little embarrassing I thought the answer was incorrect, despite being in Masters program for Electrical Engineering
I think it’s only embarrassing if you assume or claim you can’t be wrong. Humans are wrong all the time, even on topics they are experienced in.
Veritasium in the last year or two has really revived my hope that youtube science can be more than either crazy conspiracy videos or purely informational. He’s doing the closest a pop-scientist has done to science since the mythbusters, and he’s arguably added the important step of peer review into his process.
“can be more than crazy conspiracy videos”? What have you been watching to think that of youtube? Everyone knows this is a platform for Cat Videos.
This is brilliant, Derek! I’m still semi-illiterate in electricity, but now I know something fancy about it that many people don’t, haha! Great watch as always.