Comments by "Keit Hammleter" (@keithammleter3824) on "How Electricity Actually Works" video.

  1. Just to make my earlier post simpler and clearer as to what happens, and why Veritasium still hasn't got a correct understanding: In his example of a battery powering a light bulb via two parallel conductors extending outwards from the battery and bulb, the bulb does not fully light after 1m/c seconds - a very short time. The bulb gets a small energisation after 1m/c due to the characteristic impedance of the lines, and THEN, MUCH LATER, full energisation after the energy has stopped reverberating back and forth in the lines due to the end short circuits - a multiple of lv/c where l is the length of the lines in metres, and v is the impulse velocity set by the line's inductance and capacitance, this velocity is always much less than c in real set-ups. He has not made this clear in this video, indeed it appears from his focusing on the initial small step he didn't understand it. He just regurgitated what he read somewhere without having insight. Reflection occurs at the far ends because current is flowing in the end but there is no voltage drop, so the end must be imposing a voltage opposite to the voltage arriving from the battery.
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  2. 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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