The Big Misconception About Electricity

Special thanks to Dr Richard Abbott for running a real-life experiment to test the model.

Huge thanks to all of the experts we talked to for this video -- Dr Karl Berggren, Dr Bruce Hunt, Dr Paul Stanley, Dr Joe Steinmeyer, Ian Sefton, and Dr David G Vallancourt.

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References:

Hunt, B. J. (2005). The Maxwellians. Cornell University Press.

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Special thanks to Patreon supporters: Luis Felipe, Anton Ragin, Paul Peijzel, S S, Benedikt Heinen, Diffbot, Micah Mangione, Juan Benet, Ruslan Khroma, Richard Sundvall, Lee Redden, Sam Lutfi, MJP, Gnare, Nick DiCandilo, Dave Kircher, Edward Larsen, Burt Humburg, Blake Byers, Dumky, Mike Tung, Evgeny Skvortsov, Meekay, Ismail Öncü Usta, Crated Comments, Anna, Mac Malkawi, Michael Schneider, Oleksii Leonov, Jim Osmun, Tyson McDowell, Ludovic Robillard, Jim buckmaster, fanime96, Ruslan Khroma, Robert Blum, Vincent, Marinus Kuivenhoven, Alfred Wallace, Arjun Chakroborty, Joar Wandborg, Clayton Greenwell, Michael Krugman, Cy 'kkm' K'Nelson,Ron Neal

Written by Derek Muller and Petr Lebedev
Animation by Mike Radjabov and Ivy Tello
Filmed by Derek Muller and Emily Zhang
Footage of the sun by Raquel Nuno
Edited by Derek Muller
Additional video supplied by Getty Images
Music from Epidemic Sound
Produced by Derek Muller, Petr Lebedev and Emily Zhang

[hdezoo]

I’m so glad this video exists. I use to completely not even understand how electricity worked, and now I still don’t.

[ElectroBOOM]

Well well well, stepping into my territory, eh?! I shall make a video about this!!

[Lockhorns]

Thank you to Veritasium for showing us this experiment. Laying a wire halfway to the moon is expensive and takes time and effort. This shows the commitment and quality of his content, which is simply unmatched. We are delighted to have you here!

[YThome]

Very interesting. You brought me back to my years at the ninth grade at high school when I asked myself this question and made some reasonable guesses. I wish I had a teacher like you. By strange coincidence on my entry exams to Moscow University I had to explain electromagnetic induction and during rather detailed examination a professor asked me about behavior of electrons in a conductor. I presented my "reasonable guesses".
Those days exams were blind - they didn't know anything about me. But the professor smiled: "You are not from a big city?" I said, "No, I'm from Ukrainian provincial town".
"Did you read a book by Zhdanov recommended as an extra material for AP physics?"
I said, "No, there were no such a book in our library".
He smiled again: "So you figure out yourself". I got A and was accepted.

[ericlmichelsen]

I teach physics at the University of California, San Diego, including this very topic. Within an hour of watching this, I set up the experiment, and got the result. I have photographs of the experimental setup, and of the oscilloscope traces. I discussed the results at length with a physics professor friend, and we agree on the explanation. In fact, the load gets (nearly) the full voltage (almost) immediately; there is no (visible) ramp-up time, nor delay through the long wires (delay < 10 ns). This is fully consistent with transmission line theory that is well established for about a century. Dr. Muller's Veritasium series is great, but in this case, there are several claims that are incorrect, or at least misleading. There are many subtleties, and I cannot do them justice in a comment. I would enjoy talking with Dr. Muller to clear these up. For reference, I have a BS in Electrical Engineering, a PhD in physics, and I am author of "Quirky Quantum Concepts", an upper-division/graduate quantum mechanics text supplement. This is my first Youtube comment ever.

Update: I love the Veritasium series, and I have learned a lot from it. To respond to some replies: I chose the simplest case, which I think illustrates the point that power can reach the load without going the whole length of the "wings." The analysis link below the video covers the more-complicated case. My "wings" are 50' hardware store extension cords. My propagation test confirms that coiling them doesn't matter, as expected. My analysis is fully transient, and the circuit transits to steady-state DC over time. Resistance can safely be approximated as zero, but inductance and capacitance cannot, as expected by theory. My load is 270 ohm, roughly the on-resistance of a 50 W incandescent bulb. The characteristic impedance Z ~53 ohm, which is substantially less than the load; that's what's needed for the simple case of near full response nearly immediately (the load is _not_ matched to Z). In this case, the wing capacitance dominates the behavior.

Consolidating my previous reply: Examples of subtleties: Do two electrons repel each other? (a) Most people would say yes, and I agree. But one could argue (b) No, one electron creates an electric field, and that field pushes on the other electron. This is also correct; it's slightly more detailed, and from a somewhat different viewpoint, but (a) is still correct, as well. But (c) In calculating the force of (b), we use only the E-field from one electron, even though we know both produce E-fields. To use the full E-field, we have to compute force with the Maxwell stress tensor; this is also correct. There are multiple correct views one can take. The video's chain analogy is very good, and correct. Separately, a few replies have hit on the most-direct (IMO) explanation: the capacitance in the wires provides an immediate, physically short path for the electricity to reach the load. The path of current changes over time. Your gut might tell you that the capacitance is too small, but a quantitative transient analysis using standard circuit theory matches the experiment. Special Relativity still stands. More subtleties: characteristic impedance, etc. I do similar demonstrations in class, so I happen to have all the equipment and experience ready to go.

[at]

The fundamental law of physics: electricity disappear if you stop paying bills.

[mdershadulchoudhury]

As an electrical engineer and faculty, I knew it but never told students. The charges do not flow. It is electromagnetic energy transfer as explained here.

[ramontan]

Until I saw this video, I was of the [flawed] understanding that electrons are responsible for the work done. My education gave me the [wrong] impression that because current flows through a conductor, then it must be the electrons in the current that are "doing the work". Where else could it be? The mechanical analogues with water tanks also added to the incorrect understanding.

I could (and should) have also convinced myself that Work = Energy, and that current or charge are NOT units of work, so it has to come from somewhere else. But why is something that is so fundamental to a student's learning not explicitly stated in lectures and textbooks?

Thank You Veritasium and the author, for this excellent and enlightening video. And may our teachers and writers of textbooks also take note.

[MattMGK]

After watching this video I can confidently say I understand less about how electricity works than I did before.

[dylandailey]

EE here; I think most of this info is technically correct, but potentially misleading in some areas.

For one, while it's true that energy is transferred in the space around a conductor, as opposed to through the conductor, the *vast* majority of that transfer is taking place *extremely* close to the conductor (we're talking millimeters, typically), due to both the magnetic and electric field strengths decreasing exponentially with distance from the conductor. So in reality, the energy being transferred actually decreases superexponentially with distance from the conductor. Now, in power lines, the ground is still a concern because it's a very long conductor, carrying very high voltage, at very high currents; it's a somewhat extreme case. Yet, even though the cable is *miles* long, we only need to separate it from the ground by tens of meters to significantly reduce losses over that long distance. Furthermore, the ground is only a problem because power lines are AC. If they were DC, you could lay the cable right on the ground, and you wouldn't get any significant energy loss.


Edit: see below, the dropoff is not actually superexponential, but the general idea that energy transfer is greater closer to the conductor is still accurate.


For two, the analogy of electron flow being like water through a tube is actually still accurate in the case of the undersea transmission line. The metal rings around the cable cause a change in electrical impedance for that section of the cable. In the case of water in a tube, this would be analogous to having an air bubble trapped in your tube. As a pressure wave travels through the water, it will suddenly hit this air pocket, which is far more compressible than the water (i.e. has a different impedance), which will cause the waveform to distort in precisely the same manner as the electric wave does in the cable. Some energy will pass through the bubble, creating your distorted (attenuated) waveform, and the rest of the energy will actually become a wave reflected back in the other direction. This is precisely what's causing the distortions in the undersea transmission line. There's a bunch of reflected waves bounding back and forth between all the iron rings that stretch and distort the original signal. (for the real electrical nerds, check out "time domain reflectometry", which uses this principle to precisely detect where a fault exists on a power line)

Third; yes, energy transfer from the switch to the bulb will occur in 1/c time (by the way, I think you could clarify this by representing it as d/c time, where d is distance from the switch to the bulb. You never really state where the 1 comes from in that equation (at first I thought you were implying it was a constant value, unrelated to this distance)). And yes, you do clarify that it will only be a fraction of the steady state energy. But I think you should stress that this would be an *extremely* small portion of that steady state energy. The initial energy that the bulb receives will only be due to the capacitive and magnetic coupling between the two long portions of the conductor. And in the case of wire separated by 1 meter, both the capacitive and magnetic coupling would be practically zero. This again is due in part to the exponentially decaying electrical and magnetic field strengths with distance from the conductor, as well as the poor electric and magnetic permiativity of the dielectric (air) between the conductors.

Fourth; addressing your question about "why is energy transferred during one half cycle, but not returned back to the plant in the other half of the cycle", I think your physical demonstration actually explains that perfectly. No matter which end of the chain you pull, there's something down the line offering resistance to the motion of the chain. Heck, you even get friction between the chain and the tube, which is like resistance in electrical conductors. However, if you attached a sort of clock spring to your wheel (such that the spring always worked to return the wheel to its at-rest position), you would indeed see some energy returned to the power plant (you) on the second half of the cycle. This is analogous to powering a capacitive load with AC.

[TheLeftistOwl]

The thing about this explanation is that it makes so much sense when you consider how you can tap into electronics without ever physically plugging into them. You can hijack the RF frequencies emitted and recreate what's the displayed by the device. This is why the government has a specially designed devices that are made to trap those emissions and prevent signals from penetrating.

[Eden-is-Here]

This makes so much more sense than the model taught in schools.

[brockjensen]

Of course I find this video now… around 6 months ago I got into a small debate with my electrical engineering professor over a topic very similar to this. Everyone in the class seemed to be on the professors side which I guess makes sense but then the following week our professor walks into class and tells me he thought about what I was asking and had looked into it.

He walked up to the board and showed some of the similar stuff you did in this video and proclaimed I had actually been correct and my original question that countered his previous discussion he admitted to the class he was in fact wrong. This was the first time in my life I had such a crystallized idea of what someone that was truly intelligent acted like. He wasn’t upset, frustrated or hurt that his initial statement was wrong because he didn’t care about being right, he cared about the truth.

I know it sounds corny to say seeing someone look for confirmation instead of affirmation changed my outlook on life but it really did. Never before had I seen some so openly question their very own view and search for the truth rather than search for what backs up their view or idea. Great video, as always

[besmart]

I feel like a baby who just realized mom and dad don’t really disappear during peek-a-boo

[fredwilliamsonmiller]

This is a critical piece of information. In the late stages of an electrician course ( many decades beyond having completed B. Sc Mech Eng and practicing for more than 40 years as a P. Eng in the steel industry right next to the fascinating world of electrical systems. Not one syllable in over 60 years about fields as the transmission mode for the energy. Knew something did not compute....fields....the key. Thank you. Fred

[josephmarshall]

Very well illustrated! Finally, someone that really understands how electricity is conducted. Thank you! I already understood this, but I didn't know how to explain it to anyone. I will be sharing this with my colleagues.

[SparkyPeteG]

I'm an electrician from the UK.

This theory can be proven by holding a florescent tube near a power line. It will glow. My family didn't believe me so I showed them. So glad you explained this in a way they understands fully. Thankyou. Very clever.

[AndrewDotsonvideos]

And here I thought all vectors were pointing.

[VicasArav]

Wow. After so many years of confusion finally I got the answer of how Electricity is generated. Thank you so much Veritasium for making this wonderful video. Now I understood about electricity and how current flows form power stations to our homes. 👏👏👏👍👍👍

[momokoko]

God!! It's 1:30AM, I've to wake up early but why am I watching this instead of sleeping