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https://www.youtube.com/watch?v=bHIhgxav9LY
Cheat: Assuming a 12 V & 3 W LED bulb which draws 0.25 A,
and a 1.5 sq mm/ AWG 16 lead (having an inherent voltage drop of 6 V /km),
the applied battery voltage would only have to be 3 600 012 V [or 3.600012 MV].
Have a nice weekend, all! :idea:
Johan
I watched this when it first came out. It's a good video, but it's a bit hand wavy with the whole physics woo. I get the Poynting vectors and everything, but everything in this video can still be explained classically by capacitive coupling of the parallel wires. Dave Jones at EEVBlog did a really good analysis/rebuttal of the video from a classical electrical engineering perspective:
https://www.youtube.com/watch?v=VQsoG45Y_00
Science Asylum made a video about this in 2019. If you haven't checked out that channel you really should. It's spectacular. Much higher quality than most physics/science Youtube channels.
https://www.youtube.com/watch?v=C7tQJ42nGno
I guess what it comes down to is, nothing is as simple as you think it is.Quote:
Originally Posted by nova_robotics
Does all of this show a better way to do "it"? No, you've still got to have wires to set up the magnetic fields so what's the point, He's selling a product, a radio controlled switch, is that new?
No one is selling anything. There are no radios. These are videos about electrical theory.Quote:
Originally Posted by old kodger
The point is.....it's interesting.Quote:
Originally Posted by old kodger
Surprisingly, the light will illuminate at much less voltage. There are capacitive and inductive effects at work. Think of the wires as two plates of a parallel plate capacitor, or the loop as two tightly coupled dipole antennas. Even if you cut the wires (at the farthest points) the bulb would still illuminate at perhaps a few hundred, or a few thousand volts. I suspect it would also oscillate because that's essentially a giant RLC circuit with a 0 ohm termination at each end.Quote:
Originally Posted by DIYSwede
Sure, a 12 VDC LED lamp will dimly turn on at app 8 V.Quote:
Originally Posted by nova_robotics
I can sorta buy that these "nearly infinitesimally long" wires could acts as dipoles and/or as a capacitance (with a pretty big serial inductance to boot).
But then - I simply can't wrap my head around getting DC to flow continously thru a cap, transformer (or an antenna),
other than for an initial, single LED blink (and then perhaps another when disconnecting the battery) - but then that's only me.
AC is a whole different ball game, though.
2 cents
Johan
Positively irrelevant to the thread, but still funny:
Attachment 41832
Waste 10 (+22 in Pt 2) more minutes of your life watching a solution to another hypothetical reasoning/ unprovable hypothesis:
https://www.youtube.com/watch?v=kTjGWG2d_aM
No? what do you think the reference to a "smart switch available at this location at the end of the vid, is ? What do you think a smart phone is?Quote:
Originally Posted by nova_robotics
I think you only watched the first 15 seconds and the last 60 seconds of the video. I mean yes there's an ad for smart light switches at the end of the video, but that clearly has nothing at all to do with the rest of the video. It's a science video.Quote:
Originally Posted by old kodger
To be honest, I can't either. I would have been right there with you. The system is one light second in width, so we'd have at least a second of dv/dt to keep current flowing through the capacitor. And it's a fairly complex RLC network, so it would probably ring a bit... that's where my knowledge ends. I haven't taken any courses in transmission line theory and it just all turns into magic at that point. But then I was reading through the comments and and there was a bunch of conversation that was way above my pay grade. Someone seemed to come to the conclusion that just the inductance and capacitance gave 800 ohms of DC resistance. I have absolute no idea. Maybe? I dunno. I didn't even know that was possible. I will have to defer to people smarter than myself on this one. All I know is at least some current will flow as soon as you close the switch, but beyond that I really can't speak to it.Quote:
Originally Posted by DIYSwede
An attempt to insult me serves no useful purposeQuote:
Originally Posted by nova_robotics
How on Earth did you find an insult in that statement? I think you watched a few seconds at the beginning and the end, then started posting things that have nothing to do with the content of the video.Quote:
Originally Posted by old kodger
