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

Holy crap. I have degrees in engineering, have investigated numerous electrical fires and worked for decades developing electro-mechanical devices, and no Electrical Engineer has ever explained electricity this way. Things now make a lot more sense.

I studied electronics. I learned about Maxwell and Poynting... And I passed the exam. But I never before brought this (and it has not even been mentioned in all the lessons) into a context with the flow of electricity, specifically with DC. However, having heard about the basic formulas and theorys it became clear very fast ("flash") :-) Thanks for this explanation here...😄

This video should be mandatory curriculum for people trying to obtain Magnetic Particle Testing certificates. This explanation would have made the class so much easier.

I just want you to know that through several physics classes and after a decade of angrily not understanding how electrons flowing in a circle actually transmits energy, you have finally answered my question. Hallelujah, thank you for taking the time to actually explain the how instead of simply telling me to memorize equations

Wow! I’m an old engineer that spent much of my career designing radar systems. While I knew that my first impulsive answer was likely wrong, it’s been a really long time since took a college E&M physics course and first learned about Maxwell’s equations and Poynting vectors. Too, no one explained it nearly as well as you. Thanks.

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

So in theory, if we could use a box or device to block the magnetic and electrical fields the load wouldn’t work, in this case light wouldn’t turn on? Could we get a follow up video showing that? Also would be interesting to use iron fillings to show your theory in a working circuit. I’m an electrician and was never taught this thought process! This is why I love this field, always learning. Great video, keep up the great work.

This is really cool. I always thought of it as water because that's what helped me pass a circuts class in college, but I've always been curious about magnetic fields and stuff, so this answer is cooler and therefore better.

Thank you for the video and challenging the every day assumptions. I appreciate this 🎉. A couple of questions: Where and how did you prove that it takes 1/c? If you have done testing, where can I read more about the details of your test? How do we explain the impedance that happens in large conductors along with skin effect in AC, and the transient behavior in DC switching?

Interesting, but the wires would already have fields propagated through them, because one end is connected to the battery (i.e. capacitance). What happens if you adjust the experiment, and use two switches, on each pole of the battery, closed simultaneously? Does it change anything?

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

I am not so good in physics so I have a question... So if we will remove isolation from a wire and put something iron on it (or even just near it) - this iron thing will magnetize after some time? But what I definitely learned thanks to that video is that if we put a lamp near a wire, it may light after a while. Actually, I've learned it experimentally before, but now I really understand why it happened!

OMG, I am a poor student in science but exactly 2 days ago I was wondering how electricity travels in the wire, does it do like water through the pipe to be tapped by a switch. Your explanation is awesome. Now I am 65 and this knowledge may help me to understand Physics in a better way in my next Birth. Hats off to you Sir.

This video literally changed 3 times and I have watched every time it gets better 👍

I think, what actually matters, is the location of the switch. Think if you put the switch in the middle which is 0.75 * 10^8 meters away from battery and the light bulb, when you close the switch, you'll create a signal and it shall travel from the switch to the light bulb. Thus the bulb won't light up, until the signal reach the bulb which is at least 1/4s.

I'm a student preparing for neet exam and my teacher had discussed this in Allen classroom lectures.... PG sir ☺️....

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

Definitely expected a different answer - as many years ago I plugged my phone in to top-up the charge but my battery actually reduced! Taking my charge backwards instead of increasing like it is meant to do! I can't remember what phone I was using at the time but I'm sure it happened more than once from that device. But not since then. It's true, I plugged my phone in to charge and watched it count backwards to depletion! Pretty strange!

<a href="#" class="seekto" data-time="647">10:47</a> This must affect offshore wind projects that depend on long undersea cables, especially if you put them far enough out to not be eyesores from shore (usually over 30 miles). It shows that the more local an energy source is, the better.

Wow…this is going to take a while to get my head around. I’m not an electrician but I did take a practical electronics course in grade school. At that time they used the water comparison.

This is a great video, thanks for making it! What if the lamp were in a sealed room? Assuming only the conductors pass through the walls of the room into the lamp how would the energy get their to power the lamp? This is going to keep me awake at night!

I've watched this video several times trying to wrap my brain around it. If this hypothesis is true, then , using your setup with the light bulb, you should be able to disrupt the flow of energy from battery to bulb by placing a large magnetic field/shield between the battery and bulb.

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

There’s Immense Happiness watching this video ,knowing how universe actually works and understanding every bit of it Answering those baffling questions Thanks a ton @ veriritasium

I would highly recommend “story of electricity” by Jim Al-Khalili to understand the whole concept of electricity, how it was first discovered and how over time countless other technologies were developed by the discovery of electricity

Phenomenal explanation, one of the best I've ever seen and made me exclaim out aloud more than once.

This is absolutely sensible and it can easily be understood when when you look at while a lot of PCB fails today, Rick Hartley and Dan beeker already gave something about this. It's all about the space, energy travels in space not the wire, but follow the part of least impedance the wire only serve as a wave guide.

I thought I understood how current flowed in a circuit... I've been lied to in school. The actual mechanism is absolutely fascinating.

An explanation why most electrical devices only work with DC current would be interesting now! Probably because a lot of components have some kind of diodes built into them and therefore no electromagnetic fields can build up when the current vector points in the “wrong direction“…🤔

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

Well explained. Electricity is basically a mix of electron flow and magnetism that energizes the conductors.

I used to think that electrons flowed through the wires, but I eventually realized that that didn't make sense. However, I had no other explanation. This video is hard to follow, even though I'm currently studying physics/electricity, but it does give me a better idea of what is going on.

Can I get an informed opinion on the Skin Effect please when it comes to audio? Does this really have the ability to impact the performance/propagation of an audio signal being transmitted down a cable? I've heard that it does, but at most it only has about a 3% effect on the signal, if that.

you are a genius for the way you teach us this. Thank you, I have learnt so much from this channel. Everyone who watches this please pay attention, this is very intelligent information.

Great video and very interesting. I have a question though: how can we explain the wireless energy transfer using this principle where no wire/conductor is involved? (i.e. like wireless charging technology transferring energy through air based on magnetic field)

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.

It's really interesting. The yellow lines propagating from the battery to the light bulb are sort of like the Earth's magnetic field to the moon. I think this is really cool.

Those Maxwell equations mantioned at the beginning are actually vectorised reductions of his 12 original equations. The work was done by Heaviside mentioned later on. Interesting that it's fields that are claimed to carry the energy. Lorentz's special relaativity which came 4 years before Einstein's and passes all the same tests was rejected because he postulated an ether, which in my opinon is in fact a field and of course everyone accepts the Higgs field nowadays. Really once you drill down it bcomes clear that a large amound of what we are told is in fact wrong! Great video BTW.

Mr. Veritasium, This is great! I love your videos. I see here that the switch and the power supply are right next to each other. What would happen if the switch stayed where it is, but the battery was placed 300,000 km away? Is the speed at which the light turns on measured from the switch or from the power supply?

It’s refreshing to see somebody that is open to friendly debate. I can understand scientists being competitive but they never killed one another.

You should have added in the demonstration to test the circuit with a meter after hitting the breaker, simple and easily taken for granted, but would be important for someone who doesnt do any electric work. Otherwise very informative

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 KZhome 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.

I appreciate this video, thank you for the work you do and helping to move us forward.

Thank you for this nice video . Now I think we can just point a battery toward a light bulb and it will light and drop the wire as long as conductor's free electrons has no job in delevering the energy. Morevere, if EM wave need guide we can use plastic or rubber instead of conducing wires . Should this worked I would believe your thought .

Thank you. I love science and all things science. I have never understood this about electricity until this video. 😃

My mind is blown! Absolutely interesting. Makes me ponder what all this does to the human body and nature in the path…. Interesting

The production quality has become insane! You're an inspiration to all us science communicators! Keep it up! :)

I wonder if in your hypothetical model, would vaccumn effect the energy vector?

Thanks for the video. It is amazing explanation. I still have not got it 100% so need to re-watch several times.

finally some decent science information. More on Magnetic Resonance and Magnetic Fields please

very very interesting! I wonder if there would be a delay if the bulb was placed at the far end of the lines, away from the battery source?

Great effort. However, I still have a difficult time to understand how we get shocked if we touch a live wire if the electricity is not by transmitted through wires? Plus, is it then ok to say that if we physically don't connect any appliances ( bulb etc.) But have close enough connections we still get it turned on ? Please try to answer as I am curious. Once again love your work.

Speaking as an electrical engineer, electricity is the closest thing in to magic that everyday people deal with. I deal with conceptualizing electricity and electrical components every day, and you're kind of forced to think of amperes like your chain analogy, voltage like water pressure, transformers like gear boxes, etc. But you have to keep in the back of your mind the whole time "but it's not water mains or a gearbox, it's electricity". It's simple up close but a whole other different thing when you try to think of the whole power grid at once. My advice to laypeople? Learn what you can, and marvel at the physics of electricity with me! ...But call a professional if you need to wire a car charger into your garage.

It's exciting that you've managed to sensationalize this kind of knowledge!

And this is the way to do ads and product placement. Thank you for it, coming from a person who hates most ads. Non-intrusive, explicit, not distractive or ignorantly manipulative, yet sufficiently in place as you use those in the video, and who wonders what they are, can find out in the end.

After watching this Vedio I understood the answer toone question that was I asked in one of the interviews The question was "what happens to the electrons at the place Where a current carrying conductor was cut with a knife while carrying current. Now I know the right answer. Thanks for this most interesting and logical concept of flow of current in an electric conductor.

This really shakes up my own personal understanding of electricity and how it works. I think that electricity is a triad of functioning flows of which at its core importance is the potential difference in electrons. What is an electron. The difference is life and death. Light and darkness. Hot and cold.

If you broke the circuit at the far end, 1 light second away from the light/power source, at the exact same moment (assuming 'moment' exists for this thought experiment), would the lightbulb still light up until the information of the circuit break reaches it? Or would the information of the circuit break reach the electric field at the power source immediately?

I think the best part of this video isn't just the information it presents, but also the conversation it sparks in the comments! People asking questions, people trying to understand what's being said, and even people providing counter-arguments in certain scenarios where what Derek explains doesn't seem to match up. I think having civil discussions helps a ton, thanks Derek + the Veritasium community! This video and the comment section is genuinely interesting to go through

I often ask myself how much science suffers from confirmation bias. Great upload....THANKS !!! I wish everybody a positive life 🍄🌏👁😀

Great video but I have a question. When the basic circuit is connected <a href="#" class="seekto" data-time="374">6:14</a> battery´s electric field that is neccesary for the energy being send through space is extended through the circuit at the speed of light. So in theory you have to wait for the field to extend before you recieve energy right? That would mean even if you have battery and light bulb next to each other you have to wait for electric field to extend through the circuit (Wouldn´t the answer to your question be 1 second?)

I wish we were taught this in physics class

Interesting! So the motion of electrons in the cable is more like cilia in the lungs expelling objects, or a millipede's legs passing along grains of sand, or maybe a sweep rowing crew pulling a fancy maneuver. I am often attracted to your videos, but this one really sparked my imagination, thanks!

could someone explain how this interacts w' more than one object, for example instead of just one light globe, add a resistor linked in with 2 or 3 light globes and say a speaker. i see how it works and it makes sense I'm just having issues visualising it w' multiple objects in the circuit. thanks for the vid tho really usful, i may only be doing a level 2 in electronics but it still fun to dive a little deeper sometimes :)

The part about AC was mindblowing. The Poynting vector is S = E x B but if both E and B are reversed, then S = (-E) x (-B) so the energy flow stays the same!

I think it was My Dad’s high school experiment or perhaps college in the 50’s as a electrical engineer to light up a light bulb by winding copper around a long six foot diameter drain pipe if I remember correctly it was like 50 feet long . He then placed the drain pipe on the ground under those very tall high tension electrical towers . The light bulb lit up . He told me that anyone who claims they understand electricity is wrong . There exist phenomena we still don’t understand about electricity .

This is a very interesting. As a HiFi Enthusiast some of the thing I hear about cables suddenly make sense. Since no electrons are transferred it must happen in the electric field. But if I connect a Current Clamp over both wires. Then I won’t measure anything. The magnetic field created by the electrons in both wires will cancel itself out. What am I missing?

So if we cut the wire somewhere in between, do you think bulb will still turn on? Just curious if it’s electric and magnetic field around then a small cut shouldn’t matter as you suggested as well.

This is a very late question, but what about insulation? Does the insulated line limit the surrounding flux of electromagnetic energy? Does insulation limit the energy to limited area surrounding the wire itself?

A follow-up experiment should change the distance between the battery and the bulb and plot the time it takes for the bulb to light up as a function of that distance.

WOW! I'm 80 years old. Started learning electronics in the Army in 1959. We were taught the "Right Hand Rule" in the study of inductors and transformers. Although we knew about the magnetic field around conductors we never applied that knowledge like this. Thank you for teaching an old man a new trick.

A coupe of things I don’t understand: if electricity creates a kind of ‘aura’ around the wire, why are cables insulated? Presumably, this doesn’t actually insulate the electrical charge. So is it there to stop other types of signal (radio waves?) from interfering with the signal? Secondly, what about circuits scored into silicon wafers? In this case, the signal must travel via elections due to the small size of the signal path? Or do circuits like this create electromagnetic auras of their own?

I believe the bit about the Energy being in the fields, but if the 1/c answer is correct and hence the field can propagate straight through space from the battery to the bulb without having to go along the (long) wire, then this begs the question as to why the wire is necessary. You should also be able to set up a sort of „quantum erasure“ type experiment in which at the far end of the long wing loop the wire is cut through after the light bulb lights up, but before the information that the wire is no longer connected could travel or be seen at the bulb. So what happens if you connect the switch and then severe the loop at the far end at a time t 1/c< t < 1s? And when would the bulb extinguish? If it extinguishes in time less than 1second then you are successfully transmitting the information as to whether the wire is severed faster than light. you could use this to make a faster than light morse-code transmitter. Please rebutt.

It's intriguing and counter-intuitive. What if we place the light bulb inside a box shielding all EM waves?

Dang. Can't say I ever knew or even heard about that. Is this also the reason why there are so many new health problems that are acclaimed to come from Electricity? Or are those more likely to be caused by Radio waves and whatever Bluetooth and Data uses?

At the end of a very intese physics course and right after the exams, our teacher ended it by telling us that everything we had just learned about the flow of energy in an electric system was most likely wrong and mentioned something about energy not passing through the cables. Now I finally know what he meant. Thank you 😅🙇

Your video is excellent thank you, You're a great teacher

this question is always coming to my mind, and never I can find a satisfied answer ... Thank you so much

Subscribed. You're a gifted orator. Great stuff.

Such a well done video that I listened to the whole ad at the end. I dislike ads but so appreciated the information.

Very good info. I worked in the electronics/semiconductor field all my life, and confess that I always thought of it as flowing through the wire, or on the surface of the wire, when I gave it any thought at all. Of course, inductance in transformer coils are kind of a heads up that energy in transferred through the EM field in space, not wires. I suppose the wires could be thought of as the necessary scaffolding for the EM field to propagate and transfer energy.

I’ve been an electronic technician since the 90’s and I remember one of my electronics instructors explaining this to us and it still blows my mind all these years later. Fascinating video, thank you for posting.

I think this is a well-produced video that jumps to both right and wrong conclusions. Okay, energy is transmitted by the electromagnetic field. But the electrons passing through the wires play their part. Otherwise, a broken wire would conduct energy just as well as a good wire. Maybe I could agree with your answer just because of the capacitance of the proposed system, but as a RESIDUAL energy transferer.

I am a grade 12 science student and I found this video really interesting.

And at UHF frequencies, there is a phenomenon called skin effect. In electromagnetism, skin effect is the tendency of an alternating electric current to become distributed within a conductor such that the current density is largest near the surface of the conductor and decreases exponentially with greater depths in the conductor.

Thank you Veritassium. This is indeed the element of truth.

Well, while we are picking at things, my HS math teacher would slap us on the wrist if we said "over" because that is not a math function. We were required to say "divided by" since that leads to better understanding. That has stuck with me for over a half century. Cool presentation.

I think one of the most difficult things about the Poynting vector is to visualise the cross product in your mind. That video with all fields represented in space is extremely helpful and should be shown in EM courses.

Deeply intriguing. But why does a person only get shocked when he touches a circuit's conductive wire or a battery terminal? What happens then? How far outside the conductor do the electrical and magnetic fields extend? Why is there no effect if you just come into (or near?) one or both of those fields? Thank you for the video but it's taking me some effort to get the whole picture.

Is there a way to use this electricity / power from the magnetic field without touching the wire? Could you put an LED yard light (on a wooden pole) close enough to the overhead wires - that lead into my house - to turn it on? It sure seems like I could and I am going to try it.

I have a question. In many applications, we use special cables such as MI cables, super screened cables, which do increase the SNR and better /more current. How does that happen?

Very well explained, thanks

Okay, but If I stood at one of the lines extremes with a pair of scissors and cut the line, how long would it take for the light bulb to turn off? Would it take half a second for the collapse of the electromagnetic field? Or would it happen nearly instantly? If its the latter we could use a switch to transmit information nearly instantly over astromonical distances. If its the former then I'm confused as to how the field propogates to the lightbulb near instantly.

My grandmother lived on a very remote and isolated island in Norway. When they first got electricity, they had one lightbulb connection hanging from the ceiling in the best living-room (it was only used when having fine visitors). The thing was that when the electrician first lay out the cables, they had no bulb to put in the socket. Also the electricity was not yet connected to the house but would be soon. So each night they put a bucket under the empty socket just in case the electricity would be connected while they was sleeping. Not to spill anything on the floor.

The energy is extracted from the movement of the electrons at the load. It doesn't matter which direction that the electrons are moving, you can rectify it.

I'm so chuffed I got the right answer and could understand this, school served well - thank you Mr. Evans.

So how does Coax and similar signal transmission line fit into this considering it is so effective though it purposely uses a grounded shield? That sounds a lot like your trans-atlantic cable example, but with the opposite result.

I have a question, as the electrical and magnetic energy travel in space, since they're in phase, a moment occurs where both the Elec and Mag fields are 0, How does positive energy re-emerge from 0? I always thought that the peaks would be 90* out of phase, but it is said to be in phase. How is this possible?

Should have mentioned Stinemetze was the key to designing the waveguide wire also known as a low loss Coax cable. Very important person in History!!