Comments by "Keit Hammleter" (@keithammleter3824) on "Veritasium"
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@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.
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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.
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@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.
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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.
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Is this Veritasium guy clueless or just fast with his facts? He makes mistakes at detail level and and overall level.
For instance, he is wrong about the development of computing: Analogue computers took off during and after World War 2 as they were found to be effective in solving all sorts of dynamic and control systems (eg missile guidance, auto-pilots) problems. Digital computers essentially began during WW2 (in the USA for ballistic calculations; in Germany for airplane stress calculations) and took off in late 1950's due to accounting, stock control and other business application development. Analogue computers continued until the 1980's, when good applications running on cheap personal computers became available. Neither came significantly before the other.
In comparing digital computation with analogue, he's got it very wrong. It's not a case that to add 2 numbers in digital you need 50 transistors and for analogue you just need a wire connection as he claimed. Those of us who have worked on actual analogue computers know that the basic computing unit is a thing called an operational amplifier - which typically needs about 30-50 transistors (early, less accurate analogue computers used vacuum tubes in lower numbers). And just as much power,
What killed analogue computers was that with the development of good applications in the 1980's allowing fast problem set-up, digital became much cheaper and easier.
He's confused distributed (also termed parallel) processing with analogue processing. They are two different concepts. You can have distributed digital processing or serial processing. You can also have serial (termed cascaded) or distributed analogue processing.
Using MOSFETS as simple multipliers as he described is not new. But it is good only in a few niche applications due to two fundamental features of MSOFETS: 1) the current is NOT a simple product of voltage - they are not linear, and 2) it's darn hard to make them consistent - ie each MOSFET giving the same result as another. That's why general purpose analogue computers used those carefully engineered 30-transistor operational amplifiers, and not just one transistor per computing element.
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@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.
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@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.
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Gee this guy Veritasium talks nonsense. He said nuclear power is a knife edge situation, i.e., teetering on going bang. This clearly isn't so. For one, they are operated well below critical mass (There may be enough mass of the right isotope, but it is distributed over a large volume mixed with other stuff), so can't go bang. If you read anything about water moderated reactors, for example, you learn that water absorbs neutrons in proportion to its temperature, this means the reactor power level rises in beautiful proportion to control rod position (control rods are movable neutron absorbers), as increased reaction raises water temperature which slows down the reaction. It is a form of what is called a negative feedback loop. The control rods can typically control the reaction rate smoothly from beyond the design maximum down to a tiny fraction of that, practically zero.
He said Einstein claimed nuclear power and bombs are not possible. Just when and where did Einstein say this? In what publication and in what context? I know that at one point he said it couldn't be done YET. Naturally it had to be figured out, which was not easy.
Einstein famously wrote a letter to the US president to tell him that nuclear bombs are possible, and he better put resources into design and building one before an enemy does. Thus the Manhattan Project was begun. I have a book on Einstein that includes a reproduction of this letter.
But Veritasium is the guy who posted a video claiming that electric energy is not transported in wires, and included a whole lot of mistaken nonsense about propagation in transmission lines, so perhaps his videos are some kind of leg pull.
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He's a lot better in this video than he was in the first one - but he still says things that are wrong. Getting roughly the right answer doesn't necessarily mean you have a full and correct understanding of the details. Ordinary electrical tradesmen routinely apply Ohm's Law, though very very few could explain or derive it, just as anyone can competently drive a car without knowing engine thermodynamics.
He's getting closer to understanding that in a DC or low frequency AC circuit the fields outside the wires have nothing to do with conveyance of energy from battery to bulb. But he still said things like the current propagates at the speed of light. No it doesn't, because any wire has inductance and capacitance to something, which he seems to have sort of appreciated later in the video.
He's gone down a rabbit hole in saying that the electrons in a conductor are driven along by an internal field in a conductor, which is correct. The internal field is possible because practical conductors have resistance. But you can, with a bit of cooling, have a superconductor - there is no resistance and no internal field then. But those electrons, having kinetic energy, still can convey energy from a source to a load, just the same - if the source is a DC source (and in practice a low frequency AC source).
He's glossed over that the rise on voltage across his resistor was not just a simple step to the final (steady state) value - there was a an early small step due to the parallel line's characteristic impedance that he seems to have focused on. Actually, there will be a series of steps converging on the final full voltage, due to energy reflected at the short circuits at the ends of his two transmission lines, so a packet of energy goes back and forth until losses absorb it - its just that his experimental method does not resolve all the steps.
He goes on about wireless charging of battery powered devices - but this has absolutely nothing to do with whether of not energy in a simple circuit is conveyed by the electrons or not, it is merely an example of a specialised power transformer. Current (which MUST be AC) forced to flow in one winding sets up an oscillating magnetic field inducing a voltage in another winding.
Here is a thought experiment for you: Imagine a vacuum, and inside it a hot cathode, which emits electrons in all directions (thermionic emission), as electrons in a conductor have an average speed that increases with temperature, but with a statistical distribution of speed, so some of the faster electrons have enough kinetic energy to escape the positive electric field from the atom nuclei. Once these electrons escape, they keep on going. Now, imagine a sphere nearby with a small hole in it, surrounding the cathode. Electrons that happen by chance to to leave the cathode in the direction of the hole pass right through it. Connect the plate via a return wire to the cathode, otherwise other electrons hitting the sphere will build up a charge on it. Now, back to the electrons passing through the hole. They are now not subject to any applied electric field, but they will keep on going, as they have mass and inertia. Does this flow of electrons constitute a current? Yep, it sure does. Can it deliver energy to a remote conductor? Yep - it sure can. Even if the mean distance between electrons is sufficient to make inter-electron electric field interaction negligible. Because each electron carries a little bit of kinetic energy (obtained from the heat applied to the cathode in this case), as it has mass and velocity.
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