Comments by "Keit Hammleter" (@keithammleter3824) on "The Big Misconception About Electricity" video.

No you don't, because the presenter has little understanding of his subject and has made several key mistakes. He's read a few books, dropped a few names, and regurgitated without really understanding them. See my other post. Contary to his claim, electrons do carry energy - as kinetic energy (as you learnt in high school science, 1/2 m x v-squared) as they have mass. Resistance occurs when moving electrons bounce off the nuclei of atoms in a conductor, changing their direction and transferring some of their kinetic energy to the atoms. So the atoms get jostled about, which we measure as a temperature rise. And the fact that the electrons end up travelling in somewhat the wrong direction as well as loosing some speed show up as a reduced current and a voltage drop.
23
You've asked a very good question. And yes, you can obviously use a shield - and it makes absolutely no difference at all in the battery and light bulb case, where the current, which IS in the wire, is DC. Just buy some coaxial cable - use the inner conductor to carry teh current, and the outer as the shield. The shield will constitute a Faraday shield. A faraday shield is where you use a continuous conductor - and if it is a perfect conductor, no energy can go through it.
13
Very well put, and spot on. It always amuses me that people think that mathematical models are the real thing. As a working electrical engineer, I can tell you that the art is in using the right theory for when it DOES give the right answer in calculations, and another theory for when it DOESN'T.
10
@F8Tributo : At least he's read a few books and mostly regurgitated correctly, while making awful mistakes because he hasn't put it all together in his own mind. The YouTube algorithm has presented to me a few other YouTuber's answers to Veritasium. They include some right crackpots and folk who have no idea at all. None appreciate that the 2 conductors forming a primary transmission line to the left also form a tertiary transmission line with earth, between the battery & switch and the lamp, as do the 2 conductors to the right. These second order or tertiary transmission lines deliver a weak step to the lamp at 1 metre / v1 where v1 is the velocity of propagation in the 2 tertiary lines, v being always less than c. This weak step, of course, being added to by successive steps as reflections arrive from the distant ends of the primary transmission lines, each of which takes 2 x L/v2 where L is the line length and v2 is the velocity of propagation of the balanced lines - about 3 seconds each in his example. These steps get weaker so that the lamp voltage converges on the battery voltage, being substantially equal at many times 3 seconds. Actually, the weak step is actually itself a series of converging weak steps due to reflection at the lamp, as its impedance won't match the tertiary line impedance. But these steps merge into a ramp on his oscilloscope due to scope and probe limitations. Amateur physicists are always good for a laugh when they get on this topic. Rejection of the idea that energy can be transported by electrons at DC and low frequencies has got periodically rejected by the ignorant ever since electrons were discovered and understood. They forget that field theory was thought up well before electrons were understood, by chaps who wanted to explain why high frequency AC causes radiation.
6
@KirelRed : Good electrical conductors i.e., metals can be used to make a shield, as electric fields do not penetrate perfect conductors - metals are not perfect conductors but in practical situations they are good enough. Ceramic is an electrical insulator and thus cannot constitute a shield. It is however, a dielectric - a substance that intensifies an electric field. The practical effect of putting a dielectric between conductors instead of a vacuum is that the velocity at which electrical energy is transmitted form one end to the other is slowed down - to less than c (velocity of light in vacuum). I hope that helps you. This slow down still leaves the time it takes energy to travel the length of a spark plug really really insignificant compared to spark duration any any other time aspect of engine operation.
5
ScottV, I bet you learned it in a physics subject taught by the Physics Department, but if you did an engineering course, the engineering department taught you far more useful stuff. This reminds me: When I did engineering at uni, we had to do 4 units taught by the Physics department, where the staff were long-time physics academics who had never done any real work. One of the subjects they taught was a theory on how bipolar transistors work. This theory "proved" that the current gain of a transistor could never exceed about 50, and went down as current went DOWN. That more or less matched how the early transistors performed when they went into production in the 1950's. But this was the 1970's and transistors now had current gains as much as 2000, and gain reduced as current went UP. Another theory we got taught by the Physics Department predicted that LED's could only be made to emit red light. In the engineering department we were using the latest thing - commercially available orange and green LED's. (Blue and white were not then available) I disagreed with the prof in class, who dismissed me as silly. So, next class I bought in a battery powered green LED circuit. He was taken aback at first but then asserted that my green LED must be an incandescent light with an internal greed filter! The moral of this is that once physicists think up a theory they like, they just keep on teaching it, long long after commercial R&D proves their theory is wrong or only applies under certain conditions.
5
@Arcanthsos : That's not always the case. In physics, the prevailing theory is often complicated and has noticeable problems. Then someone makes a breakthrough and elucidates what's really the case. The classic example of this was where people sought to explain the movement of planets. Since it was "obvious" we can't feel or sense the Earth moving, they started by assuming it didn't. That forced them to devise the epicyclic system to explain the observed planetary movement. It allowed the positions of planets at any given time reasonably accurately. Then someone else realised all the planets including Earth actually orbited the Sun. That's mathematically much simpler yet more accurate. String theory is a currently fashionable way to explain particle physics. It's probably the particle physics equivalent to the epicyclic theory of planets - its complicated and has serious limitations. Eventually someone might discover some initial error in thinking, take a different tack, and it will become simpler. In Edison's day, electrical engineering calculations were always complicated and lengthy, until an early General Electric engineer realised you could used vector algebra, and such calculations became vastly simpler. Vector algebra is not just a simple abstraction, it accurately describes just what is happening.
4
@Mark T : You seem to be very confused. There is no magnetic field outside a coax cable - since the centre line of both inner and outer conductors is coincident in space (that's what coaxial means) and the currents are equal and opposite, there is full magnetic field cancellation outside the outer i.e., there is no magnetic field outside, There obviously IS a local magnetic field inside the outer conductor and close to the inner, as the inner conductor has measurable inductance, e.g., RG-174 coax has 252 nanohenries per meter. Google inductance if you don't know what it is. A wire cannot have inductance without a magnetic field, therefore there is one within and just outside the inner conductor (where current density is high). But not outside the outer - that's part of the reason why coax is used. You can run 2 or more coax cables side by side and there is no coupling. It's done all the time in telecoms carrier offices. Since Veritasium assumed zero resistance conductors one light-second long and perfectly straight, he's talking theory, so it's ok for me to talk theory by citing diamagnetics, even though there are no known diamagnetic substances good enough for this application in practice. You can indeed block magnetic fields with substances displaying Meisner Effect - look it up. You can block AC magnetic fields with a Faraday cage, for the reason I gave. Look that up as well. Look inside any analogue radio - you'll typically see 4 or 5 little aluminum cans - these are preventing the magnetic fields from the wire coils inside them for interfering with each other. In transistor radios they are typically about 1 cm cubed. In old vacuum tube radios they can be up to 70 or 80 mm high and up to 30 x 30 mm cross section, but they all do the same thing - confine magnetic fields created by wire coils to the inside of each can.
2
@harrishanley8104 : Exactly. And in both chemistry and electronic engineering, when you drill down, you have to understand the behavior of electrons. In some circumstances the darn things behave as waves, and we do calculations based on wavs and get the right answer (that is, and answer that gives the right practical result), but sometimes they behave as tiny little ballistic particles, and we do calculations based on particles and get the right answer. It depends on the circumstances. It doesn't mean that electrons (or other charge-carrying things for that matter) somehow flip between being waves and being particles - it means we didn't actually figure out just exactly what electrons are and what makes them tick, but we have discovered when wave theory works and when particle theory works. And then particle physicists came along and pointed out that electrons captured by a nucleus must be a statistical probability ....
2
I'm glad this twerp was not the lecturer teaching me electrical fundamentals all those years ago at university. He is so confused, and confusing, on lots of points, and missed vital steps in reasoning. He's made a lot of mistakes - the biggest being his claim that electrons don't convey energy. Firstly, in his battery and light bulb example, there is NO energy being sent in fields outside the wires - because it is operating at DC. As an earlier poster suggested, you can cover each of the wires with a faraday shield, at as close a spacing as you want, and it will make no difference - the bulb will still light just the same. At the very low frequencies used in electric power distribution, the situation is practically the same as for DC - radiation is minute, and the useful energy is conveyed by the electrons moving in the wires. The early undersea cables only work at slow speeds because of shunt capacitance and series inductance - these involve local fields (electric field in the case of capacitance, magnetic field in the case of inductance) but do not necessarily involve radiation of energy. He claims power transmission lines have the wires in air far apart on high towers because the energy is flowing outside the wires. This is not so. It's done that way, sometimes (only sometimes), because plastic insulation to handle the very high voltages sometimes used is expensive, and so is burying cable in the ground. But most electric power IS distributed in closely spaced wires in underground cables. The fact is, electrons (and other types of charge carrier) have mass - and this means they can exchange electric energy for kinetic energy and back again. In fact, that is how we can calculate the mass of an electron - use an electric field to accelerate some electrons (a few kilovolts will bring them to a good fraction of the speed of light), and slam them into a conductive plate, bringing them almost to a stop. The plate will get heated, as the electron's kinetic energy has to go somewhere - it gets transformed into heat, raising the plate temperature, which we can measure. So, electrons can, and do, carry energy from one place to another - as kinetic energy. The mass of an electron is tiny, but there is a heck of a lot of them. This twerp has made a classic mistake in physics - he's read some books, but only half understood them, because he has not played around with practical examples - and so has not realised that much of electromagnetic theory is just a collection of man-made mathematical fictions that generally does give the right answer, IF you apply it where it DOES apply, and use a different theory when it DOESN'T. In short, a mathematic model is a model, it is not the real thing. It's worth noting that electromagnetic theory, Pointing vectors, Maxwell's equations, etc, was developed well before it was realised that there are such things as electrons, ions, and other sub-atomic things that has mass and charge, ans so can convey energy. Until electrons were known about, it was a complete mystery to those early theorists how DC circuits worked. They went around teaching each other that energy is not carried in wires, but practical electricians had to assume it was, due to things like wires getting hot carrying a current (which doesn't happen in a superconductor), and intimate contact being needed between conductors. Not to mention that a DC and the low frequencies used for power distribution, you can bundle the wires for several circuits together and it works just fine (not at radio frequencies of course). The discovery of electrons was quite an Ahah! moment in electrical engineering.
1
@imuserable : Because they are bigger than you and can enforce their demands.
1
@karlylesparents7783 : Just because he CLAIMS it applies to DC doesn't mean it does. He seems to think that current is dragged along the wire because of longitudinal electric field in the wire. But in wires made of superconductors, the is zero resistance and therefore no electric field. Superconductors do of course work perfectly well in transferring energy from source to load. Same with electron jets in vacuum - no resistance, and no longitudinal field. People who don't understand their topic make claims all the time - it doesn't mean they are correct. Some people claim the earth is flat and have dream up all sorts or mumbo-jumbo to "prove" it. But it's not flat, as any navigator knows.
1
@karlylesparents7783 : Ah, but it prevents those inside fields from getting out, too. And since Veritasium presented a theoretical discussion with zero resistance wires 1 light-second long etc, we can also assume the separation between inner and outer conductors in the coax approaches zero but is still insulating. If that doesn't satisfy you, consider an electron jet in vacuum. There is a space charge around it, but if you have a positive ion jet going in the opposite direction, you still have an electric current (being the sum of both) but the electric fields cancel. Or just have a very long electron jet in vacuum. You can replace any or all wire in a circuit with an electron jet in vacuum. It transports energy from source to load just fine without resistance due to electrons having mass and thus inertia. The electric and magnetic fields around conductors in a DC circuit carry no energy because they are not moving/changing as they are with AC. This is something we learn in the first week of any diploma or degree course in electrical engineering.
1
@weblure Actually, in this video at least, he hasn't actually presented any pseudoscience. What he's done is read a few textbooks and regurgitate bits of the various contents without understanding it in his own mind and so making some whooper errors, and drawing wrong conclusions. He presented a transmission line problem, gave what he thinks is the correct solution, but it isn't. Amazingly, he also (wantonly??) totally miss-understood what the oscilloscope told him, to fit his pre-conceived erroneous view. He claims the lamp is lit at 1 second / v. It isn't, it takes a lot longer, due to reflections on the secondary transmission line formed by his extended conductors, said reflections have to die out in steps each lasting 2 sec / v. He didn't realise that his left transmission line and his right transmission lines together actually form a third, secondary, transmission line, mismatched to his load (the lamp). His explanation of a DC circuit in terms of Poynting vectors etc is just a total mix-up. Veritasium is actually a Dereck Murray according to the link he provided, who claims to have been a science teacher and have a physics degree. That's a horrifying thought, given he "teaches" miss-conceptions. If he does actually have a physics degree, he must have just scraped a pass if this video is anything to go by. If he does.
1
@Mark T Not correct. There are two main ways, depending on whether the field is AC or DC. If it is an AC field you can stop it with a continuously surrounding conductor. The magnetic field induces a voltage in the conductor, which causes a current in it - this current produces its own magnetic field which is in the opposite direction and so cancels out the first magnetic field. This is called a Faraday screen, and is a technique used in virtually all non-digital radio receivers and transmitters, but will work down to as low a frequency as needed. Coaxial cable can be a Faraday screen for wires. No magnetic field penetrates the outer conductor. In electricity distribution, where wires carry electric power down streets, the magnetic field from the wires can cause problems by inducing into telephone lines and other things. Where this is a problem, an extra, earthed, wire is added by the power authority. It works much the same way, induction causes a current in it, which cancels the problem field, If it is a DC (unchanging) magnetic field, there is no induction and so a Faraday screen will not work. Often where this is a problem, a magnetic shunt is used - a material having a high magnetic permeability attracts the filed into itself, leaving not much field strength to go elsewhere. Or, in theory, you can use a diamagnetic material - diamagnetic materials are materials that repel a magnetic field - the opposite of what soft iron does. In practice, only weak diamagnetic materials are known, but the theory is fine. You can also use the Meisner Effect to stop a DC or AC magnetic field. Several good Meisner Effect materials are known.
1
@Mark T ; I didn't agree with you, because you were plain wrong. It sure sounds like you are upset to be shown wrong so easily. If you post an opinion that is plain wrong, you should expect someone will point it out. With or without practical examples.
1
@TerrythePhysicist : No. V, I, R, P are EXACT solutions - as any engineer knows, and as explained in engineering textbooks, even physics textbooks such as Kittel's Introduction To Solid State - a standard textbook in universities in English-speaking parts of the world. The US National Bureau of Standards has spent over 100 years progressively refining the precision of instruments to measure such quantities. The fact that practical R is always contaminated with a bit of C and L and vice versa does not invalidate this. The field theory from Poynting etc was dreamed up to explain things like Heinrich Hertz discovering that if a resonant circuit near to but not connected to another resonant circuit can receive energy, via radio waves as we now know, before anybody was concerned with DC circuits and long before electrons and other charge carriers were known about. Field theory can be applied to DC circuits in the sense no DC circuit proves the theory wrong (though Veritasium applies it incorrectly), but it doesn't explain how all DC circuits actually work.
1
@kamillugha893 : When I was doing a bachelor of engineering course at university, I tutored an African student who was doing a diploma course in electronics technology at a trade school. He was forced to learn some worthless topics for which the only available text book was one written by the trade school teacher. At least at my university, teaching staff specifying or using textbooks they had themselves written was considered unethical. Not one of the 50 or so specified books were locally written. Some of the staff had written books but if they were specified in a course, it was a course not taught at that university.
1
@weightlifting_socialist : Fair enough. Though, as an engineer, I recognise that we engineers follow in the trails blazed by the physicists, but the physicists don't seem to acknowledge that we engineers have more talents.
1