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| Veritasium "How Electricity Actually Works" |
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| aetherist:
--- Quote from: bsfeechannel on May 08, 2022, 03:06:09 am --- --- Quote from: Naej on May 07, 2022, 11:22:27 pm ---It certainly deserves to be separated because the physical behavior is quite different: --- End quote --- Separated. Since the 19th century, everybody thought that everything electric and magnetic, from DC to cosmic rays, through radio waves, heat, light, ultraviolet, X-rays and whatnot, is the manifestation of the same freaking physical phenomenon. Now you're saying that they are different. I wonder why the Nobel Committee has not noticed you yet. --- Quote ---Yes I can. Energy flows in wires and reappear in a lightbulb/engine/LED. --- End quote --- --- Quote ---Yes energy is transferred from the battery to the short, through the wire. --- End quote --- If you say so, it must be true. --- End quote --- I am not sure about the gist of this argument, but, radio waves are not photons, & photons are not radio waves. Radio waves are em radiation. Photons are photons, they emit em radiation. |
| hamster_nz:
--- Quote from: electrodacus on May 08, 2022, 03:24:13 am --- --- Quote from: hamster_nz on May 08, 2022, 03:00:08 am --- I've put a pair of LEDs between two caps, with a current limiting resistor. Where is the energy coming from that is making these LED glow? I've used 2 LEDs so you can be sure that I am not playing any funny games with AC. One glows when DC voltage is applied, the other when the caps are discharged after DC is removed. I can repeat the cycle over and over, so more energy is getting to the LEDs somehow, and charges are moving through the LEDs... but you say this energy is not going through the capacitors? --- End quote --- Use a battery. You have a low quality power supply that has a lot of ripple thus your capacitors are charged and discharged continuously. Is basically an AC supply with a DC offset. --- End quote --- My admittedly low quality PSU, replaced with a 9V battery. Same result. Also if it was an AC supply, both LEDs would glow. |
| electrodacus:
--- Quote from: hamster_nz on May 08, 2022, 03:58:06 am --- My admittedly low quality PSU, replaced with a 9V battery. Same result. Also if it was an AC supply, both LEDs would glow. --- End quote --- Not sure what you are doing there. Where is the black cable connected ? I see just what looks like a red banana plug that you touch on either positive or negative of a 9V battery. |
| hamster_nz:
--- Quote from: electrodacus on May 08, 2022, 04:10:57 am --- --- Quote from: hamster_nz on May 08, 2022, 03:58:06 am --- My admittedly low quality PSU, replaced with a 9V battery. Same result. Also if it was an AC supply, both LEDs would glow. --- End quote --- Not sure what you are doing there. Where is the black cable connected ? I see just what looks like a red banana plug that you touch on either positive or negative of a 9V battery. --- End quote --- Black cable is held against the negative of the 9V battery. |
| electrodacus:
--- Quote from: hamster_nz on May 08, 2022, 04:13:21 am --- Black cable is held against the negative of the 9V battery. --- End quote --- I see so you where charging and discharging the capacitors. LED's can glow at a few uA so it will take quite some time for them to dim as capacitors charge and those capacitors may have leakage current in that region. I just tested with a large 4700uF 35Vdc new capacitor and my small white LED had a small glow even after 30 to 50 seconds (did not count) the same level of glow it has if it conducts through my finger so I suspect a few nA I never used electrolytic capacitors in any of my projects and did a quick search and it seems they do have some leakage current due to the type of electrolyte they use. Water based ones have the largest leakage but all have even a few uA much more than nA modern LED's can glow at. So I learned something new and that is that electrolytics are not just capacitors but also a parallel resistor. There are good reason I never consider electrolytics for my projects (I do not like things with finite life). Edit: This is the exact one that I just used https://www.mouser.ca/ProductDetail/United-Chemi-Con/EGPA350ELL472MM40S?qs=beQ1fBGcmj2M%2Fui1vdONPg%3D%3D Looking at the spec it has 4uA of leakage current so fairly significant and this is not a non brand and purchased from mouser. Is just there on first page and that 4uA is best case can bemore https://www.mouser.ca/datasheet/2/420/GPALL_e-2509122.pdf In my particular case should be about 705uA based on use case 8V battery 3V on LED so 5V on the capacitor 5V * 4700uF * 0.03 but mine was no where near close to that probably is worse case and was more like 10uA max based on almost invisible glow. |
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