Initial reaction to the Veritasium video 'The Big Misconception About Electricity'

READ THE FULL DESCRIPTION:
My initial reaction to hearing ABOUT the Veritasium video on electricity energy transmission, WITHOUT having watched it or even knowing the title. Extract from the live show.

I released this for the benefit of the forum to show how it's potentially interesting to see what an initial engineering reaction is to the concept, with my mind instantly going to skin effect and that energy is in the electromagnetic field, and that "he's probably not wrong", but it's not a practical way of looking at it. Enter transmission line theory etc. All without having watched video, or knowing the title, I instantly knew it's a physics impracticality trap.
I suspect that would be most engineers initial reaction as well?

My botton line comment after having watched it:
If it was titled something like "How energy flows in electromagnetic fields", and the sensationalist title and stuff was left out, then it becomes a very valuable explanation video.
But the way it's titled and scripted, one could argue it does more harm than good. Especially for engineering students.
There is nothing new here for an engineering student. We are taught about (slow) electron drift velocity, and why and how energy is stored and transported in electric and magentic fields, it's all fundamental stuff. Ultimately this is a (simple) practical engineering question involving transmission lines, and that's what they were learning at the time with the underseas cabe thing.
It's basically just picking a physics fight like Walter Lewin did with KVL, and Electroboom calling him out from the practical engineering aspect.
The fact that transmission lines were not mentioned at all, when it is in practice a simple transmission line problem, is very disingenuous. It's borderline physics trolling.

As per the video, with the long line either side and battery and switch in the middle, the light bulb lights up briefly almost instantaneously due to the nearby distributed cable capaciatnce. Then you have a standard transmission line propagation in either direction.

The REAL question comes when you hit steady state DC. Given the question is about ENERGY transfer, how does the electromagnetic field transport the POWER/ENERGY to the light bulb under DC steady condition, with an electron drift velocity of mm/s, and a non-moving magnetic field surrounding the wire. The answer is, the power no longer flows *outside* the wire, it flows *inside* wire, obeying ohms law and basic steady state DC theory. Sure, the Poynting vector physics still works at DC, but it's of *zero practical value* to think of it this way.

So veritasium is RIGHT, but his argument is POINTLESS when it comes to steady state DC (or LF) power transfer. At HF AC the power/energy indeed travels in the electromagnetic field. It's best to think of the magnetic field as just an annoying side effect of the DC current flow in the wire.
This is why physics course don't produce practicing engineers.

I'm THINKING about doing a video on this, discussion here:

Buy anything through that link and Dave gets a commission at no cost to you.

Donate With Bitcoin & Other Crypto Currencies!

#ElectronicsCreators #Veritasium #Reaction

[EEVblog]

READ THE DESCRIPTION!
When I did this reaction I had NOT watched it!
I probably shouldn't have even released this video, I was just editing this for a potential full video on the topic.

[donepearce]

As a designer of microwave electronics for satellite systems, fields were all I considered. Current is a bit of a red herring because what you are really transferring is energy. From that point of view I have no problem with it flowing through a capacitor. The thing is that an electromagnetic field makes an electron accelerate, and an accelerating electron generates an electromagnetic field. So you can't pull them apart.
For low frequencies current is a handy way to think of electrical flow, but that model craps out when you get to GHz; Then James Clark comes into his own and his three equations are the basis for all calculations.

[Derpy]

I love how Veritasium has created this discourse across all of these other channels. It’s not competition. It’s learning. It’s discussion. It stimulates us to talk about things.

[tomg]

In the end it, was basically just two dipole antennas which are electromagnetically coupled, not even taking into account the inverse cube law for near fields. What he said was technically correct, but very misleading in my opinion.

[StreuB]

My response to that video was....

Electrical engineers and Physicists: *BOXING*
RF Engineers: *"Well yes, but no...."*

[Graham_Wideman]

As I posted on Veritasium's video: This turns out to be a simple transmission-line problem. First replace the battery with a pair of half batteries in series, and the bulb with a pair of half-light-bulbs in series. Now since the entire apparatus is symmetrical, the junctions at the middle of the pair of batteries, and at the middle of the pair of bulbs, will remain at zero volts (referenced to some external ground) and equal to each other. Now you can throw away half of the apparatus, and connect together what were the zero-volt battery and bulb midpoints.
Now the apparatus becomes a transmission line 150 Mm long, shorted at the end. We normally model a transmission line with distributed incremental capacitance (between the wires) and inductance (along the wires). Ie: the electric and magnetic fields are accounted for in these components. This gives the transmission line a characteristic impedance. So when the switch is closed, yes indeed current starts to flow.. into the nearest inductor-capacitors, and then as that voltage and current propagates further, our local current has to continue "replenishing" the nearest inductors and capacitors.
If you just have the pairs of wires loosely arranged as at 0:05, about a meter apart, and say 12 AWG (2 mm dia, convenient 1mm radius) that impedance will be something like 276 x log(1000) = 830 ohm. So with the 12V battery depicted, you would get a maximum I = 12/830 = 14 mA. If that light bulb is a single LED, it would glow as soon as the switch is closed. However, it looks like a mains-powered LED bulb, and since those run on 120V, it's not going to do anything.
Worse, the transmission line view is only valid if there's negligible interaction with external objects, such as in space. But here Derek portrays the experiment laid out in the desert., with the wires in much closer proximity to the ground than to each other. So this experiment would be dominated by capacitance between the wires and ground, and all the ambiguities that entails.

[reversetransistor]

Yes, current is displaced in the capacitor through the dielectric, but the electric permeability (u) is to low.

[mcconkeyb]

Derek's video is an intentional mis-direction of information. He doesn't give enough information to determine the correct answer to the questions posed. He then goes on to answer these questions in a way to make the viewer think that they know nothing about the subject of energy flow via electric conduction. So I had to point this out to him on his video, but haven't seen any replies.

[Afrotechmods]

He should not have written the script with the light bulb demo. He should have used a high impedance voltmeter, a spectrum analyzer, RF power meter or something else to prove the point.

[zuli]

I'm by no means an EE expert, but I immediately thought of length-matched traces in high speed communication interfaces. His explanation of the experiment seems to glance over signal propagation delays and it makes me feel like we shouldn't even need length matching. This is obviously in stark contrast with what we have to do in real-world PCB designs.

[syproful]

I love how this straightforward questions he asks. Ends in everyone going wild, trying to resolve the question. It’s exactly what he wants.

[TobyRobb]

Have been trying to teach some of these concepts for years. Electrons don't move in the wire at the speed of light! Geez my voice works at the speed of sound, but im not shooting out particles of air at the speed of sound into your ear drums!

[RobertSzasz]

An infinitely sensitive "light bulb" would light up with only light speed delay from the switch closing. Of course it would also light up as soon as anything, anywhere, moved.

I think you could model it with coax, shorted at both ends and with gap in both shield and core at the middle, measure the power transfered across the shield gap when voltage is applied to the core.

[pyromen]

I had a big issue with the video because he structured everything in a way that would convince many people that you can instantly check for continuity in an infinitely large wire loop.

[curtstacy]

The RF guys can light that bulb with no wires. just use 200 watts and a fluorescent bulb. and that was what I kept thinking of is what frequency? because many things were correct (mostly) if you use AC. maybe I'll have to watch it again. maybe I missed something.

[dave]

Hey there Dave. :) Yes Derek is a physicist. He got his education down under so I would thought you might say "good enough for Australia!" ;) He actually started out as the Australian "Mr. Proton". So Yes he is totally looking at this from a Physicist's perspective and although it didn't mention velocity factor of a wire or i2R he did say "let's ignore the resistance of the cable going to the moon and back..." Which I'm my perception was his way of trying to not consider those factors and only look at the "energy" or what later went into the magnetic fields which he later called energy. You accurately point out that this is 100% like your capacitance video. Electronic trained personal will have heard of inductance susceptance and reluctance if we would consider resistance with a phase angle then we wouldn't be ignoring the resistance of the feedline, but this might be getting back into a physics discussion. Enjoy 🙂.

[therealjammit]

A laser in free space is the same as a current flowing in a wire. We can bounce a laser between two mirrors that are positioned to cause multiple reflections. We can make these reflections bounce back and forth enough for it to take a second to "bounce" out. We can time how long it takes to remove the laser shutter for the laser power to hit a light sensor.

[frogandspanner]

2:33 "[Physics] That's useless . . . to a practical electronics engineer". The secret is to bang the rocks together, guys!

[johnneighbor]

I soon as you said "skin effect", I was like "at what frequency?"

[joegee]

The electrons don't flow through capacitors, or transformers for that matter, but the energy does.