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| "Veritasium" (YT) - "The Big Misconception About Electricity" ? |
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| Berni:
The 2/3c velocity factor is only a rule of thumb! Here are the velocity factors for some of the common coax cables: https://www.febo.com/reference/cable_data.html The PE insulated version of RG6 (cable TV cable) or the classical RG58 is indeed 2/3c (66% speed of light) but there are lots of other cable types that are significantly faster than that. This is because they separate the conductors using different dielectric materials or even just use the same dielectric material in a different physical layout (such as foam or hollow grid) Simply enamel coating a wire does not put a magical 2/3c speed limit on those electrons! You would need to cast both wires into a solid block of enamel resin for it to have this drastic of an effect on the velocity factor. If you have mostly air between the conductors the velocity factor is mostly determined by dielectric properties of air. |
| aetherist:
--- Quote from: Berni on May 02, 2022, 08:12:36 am ---The 2/3c velocity factor is only a rule of thumb! Here are the velocity factors for some of the common coax cables: https://www.febo.com/reference/cable_data.html The PE insulated version of RG6 (cable TV cable) or the classical RG58 is indeed 2/3c (66% speed of light) but there are lots of other cable types that are significantly faster than that. This is because they separate the conductors using different dielectric materials or even just use the same dielectric material in a different physical layout (such as foam or hollow grid) Simply enamel coating a wire does not put a magical 2/3c speed limit on those electrons! You would need to cast both wires into a solid block of enamel resin for it to have this drastic of an effect on the velocity factor. If you have mostly air between the conductors the velocity factor is mostly determined by dielectric properties of air. --- End quote --- Those charts go as low as VF 66 which is 2c/3. The higher VFs for some cables are due to air (foam). But, they are i think for coax. Veritasium & AlphaPhoenix & Co are all using plain wire (with enamel) or plain tubing (no enamel). I am fairly sure that a thin coating of enamel gives a VF of 66 (for wire or tube). And that thicker coatings give a VF of 66. And that a mile thick coating would give a VF of 66. At some extreme thinness (say 0.001 mm)(enamel) the VF might start to rise. And would go to 100 at zero enamel. U would think that this stuff would have been done to death by now. Re a VF of 66 for a tube with enamel. I meant enamel on the outside. But it raises the question of what the VF would be for (a) enamel on the outside, or (b) enamel on the inside, or (c) enamel on both inside & outside, & of course (d) no enamel. |
| Naej:
--- Quote from: bsfeechannel on May 02, 2022, 01:33:44 am --- --- Quote from: Naej on May 01, 2022, 08:19:00 pm ---Nah, the antennae successfully worked, and the capacitors charged as predicted. --- End quote --- Exactly. That's why I said that invoking antennas and, now, capacitors won't save your claim. These two devices show that energy resides in the fields present outside their respective conductors. --- End quote --- I'm not sure what claim it is supposed to save, but these devices illustrate that electrons can push on electrons outside their conductor. To absolutely no one's surprise. They do not, in any way, prove that energy resides in the vacuum; and indeed anyone can check that neither you nor Derek gave any proof of this (it does not exist, it cannot exist). --- Quote from: bsfeechannel on May 02, 2022, 01:33:44 am --- --- Quote ---Looks to me like another win for Maxwell's equations, but you are free to give a participation trophy to Poynting instead. --- End quote --- Oh yeah. All of them are winners: Maxwell, Heaviside, Poynting, you name it. What they predicted Nature confirmed, saving us to have to give ears to "influencers" and crackpots. --- End quote --- It's a win for Maxwell's equations, but if you want to attribute it to Poynting, Plato or Derek, well I'm a bit puzzled but why not. |
| Berni:
--- Quote from: aetherist on May 02, 2022, 09:05:35 am ---Those charts go as low as VF 66 which is 2c/3. The higher VFs for some cables are due to air (foam). But, they are i think for coax. Veritasium & AlphaPhoenix & Co are all using plain wire (with enamel) or plain tubing (no enamel). I am fairly sure that a thin coating of enamel gives a VF of 66 (for wire or tube). And that thicker coatings give a VF of 66. And that a mile thick coating would give a VF of 66. At some extreme thinness (say 0.001 mm)(enamel) the VF might start to rise. And would go to 100 at zero enamel. U would think that this stuff would have been done to death by now. Re a VF of 66 for a tube with enamel. I meant enamel on the outside. But it raises the question of what the VF would be for (a) enamel on the outside, or (b) enamel on the inside, or (c) enamel on both inside & outside, & of course (d) no enamel. --- End quote --- So at what thickness does the enamel change the propagation speed from 1c to 2/3c? 1 atom thick? 100 atoms? 10um? 100um? 1mm? Copper oxide is also a dielectric, so do signals also travel slower trough heavily oxidized copper wires? Here you can find a table of the velocity factor for twin line cables made by Wireman: https://www.dj0ip.de/open-wire-fed-ant/openwire-info/ As you can see the velocity factor from the table is 0.91, making it even faster than the fast types of coax. Yet the copper wires are surrounded by insulation, so why is it faster than coax? The reason is that most of the volume between the conductors is air (This is why they are useful, as air is low loss). The equation for velocity factor is this: So it shows that the speed is only determined by the relative permeability of the insulator. When you mix different insulators you get a permeability somewhere in between. When the wire is insulated on the surface with plastic and then separated by air then you get a permeability somewhere in between plastic and air, the more plastic you have the closer the permeability will be to plastic. In the case of twin line transmission lines yes there is plastic all the way between (since that is what holds the wires the correct distance apart) but the electric field doesn't just go straight, it also curves around, taking a path that is mostly trough air. So by your logic if you build a capacitor from two 1cm separated metal plates, then put a thin plastic foil on each plate you expect to get the same result as if there was a 1cm solid block of plastic between the plates. This is not the case. The capacitor with the thick block of plastic will have a higher capacitance since the average dielectric permeability of the space between the plates is higher. EDIT: Fixed link |
| aetherist:
--- Quote from: Berni on May 02, 2022, 10:41:05 am --- --- Quote from: aetherist on May 02, 2022, 09:05:35 am ---Those charts go as low as VF 66 which is 2c/3. The higher VFs for some cables are due to air (foam). But, they are i think for coax. Veritasium & AlphaPhoenix & Co are all using plain wire (with enamel) or plain tubing (no enamel). I am fairly sure that a thin coating of enamel gives a VF of 66 (for wire or tube). And that thicker coatings give a VF of 66. And that a mile thick coating would give a VF of 66. At some extreme thinness (say 0.001 mm)(enamel) the VF might start to rise. And would go to 100 at zero enamel. U would think that this stuff would have been done to death by now. Re a VF of 66 for a tube with enamel. I meant enamel on the outside. But it raises the question of what the VF would be for (a) enamel on the outside, or (b) enamel on the inside, or (c) enamel on both inside & outside, & of course (d) no enamel. --- End quote --- So at what thickness does the enamel change the propagation speed from 1c to 2/3c? 1 atom thick? 100 atoms? 10um? 100um? 1mm? Copper oxide is also a dielectric, so do signals also travel slower trough heavily oxidized copper wires? Here you can find a table of the velocity factor for twin line cables made by Wireman: https://www.dj0ip.de/open-wire-fed-ant/openwire-info/ As you can see the velocity factor from the table is 0.91, making it even faster than the fast types of coax. Yet the copper wires are surrounded by insulation, so why is it faster than coax? The reason is that most of the volume between the conductors is air (This is why they are useful, as air is low loss). The equation for velocity factor is this: So it shows that the speed is only determined by the relative permeability of the insulator. When you mix different insulators you get a permeability somewhere in between. When the wire is insulated on the surface with plastic and then separated by air then you get a permeability somewhere in between plastic and air, the more plastic you have the closer the permeability will be to plastic. In the case of twin line transmission lines yes there is plastic all the way between (since that is what holds the wires the correct distance apart) but the electric field doesn't just go straight, it also curves around, taking a path that is mostly trough air. So by your logic if you build a capacitor from two 1cm separated metal plates, then put a thin plastic foil on each plate you expect to get the same result as if there was a 1cm solid block of plastic between the plates. This is not the case. The capacitor with the thick block of plastic will have a higher capacitance since the average dielectric permeability of the space between the plates is higher. EDIT: Fixed link --- End quote --- Yes i think that i have come across radio hams quoting VFs of nearly 100 for coated wires, even tho i reckon that it should be 66. It might have something to do with the way they insert that number into their equations for very high frequency stuff. I feel sure that for DC or for DC transients or for low frequency stuff & standard AC that the VF for twin lead & ladderline is 66. I reckon that DC propagates slower than c if the wire has surface corrosion. Surprisingly i don’t think that anyone has ever dunn the tests to see how enamel thickness affects the speed of electricity. A capacitor with a thick layer of plastic tween the plates will have a higher capacitance. A capacitor with a thin coating of plastic will have a slower discharge (than a non-coated capacitor), koz the speed of elekticity along & over & around the plates will be 2c/3. |
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