What do you mean?Not a big fan of this video. While it's technically correct, it's extremely misleading. The power induced through the bulb when the switch closes is due to RF. It would be induced even if the bulb was disconnected from the circuit at the far ends of the wire loop.
If the entire circuit was shielded including the battery, switch and bulb, it would take 1s to notice anything at the bulb.
They basically leave viewers questioning their understanding of electricity due to a minor technicality.
I did confirm that the field propagation is limited by c. Seems like it should take a second for the field to propagate that distance and it should follow the wire. I wouldn't think the EM force could reach the bulb a meter away with enough force to do anything.The key is in the fact that the battery and light are right next to each other.... not that the wires are so long.
Consequently, the energy is not traveling FTL. But I have to admit that I don't really understand the physics of it.
I think a lot of people imagine the electrical field needs to travel from the battery, all the way down the wire which is a light-second long so it should take a second for the bulb to light up. But what we've learned in this video is it's not really what's happening in the wires, it's what happens around the wires and the electric and magnetic fields can propagate out through space to this light bulb which is only 1 meter away in a few nanoseconds. So, that is the limiting factor for the lightbulb turning on.
Now, the bulb won't receive the entire voltage of the battery immediately. It'll be some fraction which depends on the impedance of these lines and the impedance of the bulb.
I believe that's what Tesla was trying to accomplish with wireless power (e.g., if all it takes for energy to flow is an electrical field in sync with a magnetic field, then you could couple Earth's existing magnetic field with an electrical field to distribute power wirelessly worldwide).
If you add two more switches to the circuit at opposite ends where the wire bends - and open those two switches half a second before you flip the main switch - you'll still see some RF (+ maybe capacitance?) induced voltage at the bulb even thought the circuit is incomplete.What do you mean?
If the wires were disconnected?