General > General Technical Chat

Veritasium "How Electricity Actually Works"

<< < (45/185) > >>

electrodacus:

--- Quote from: T3sl4co1l on May 06, 2022, 05:48:15 am ---Whelp... time for another experiment I guess.

Ed: You're not just thinking parallel (shunt), right?  You know what I mean by "series"?

Tim

--- End quote ---

If you want to do the experiment then in order to make things simpler for you just select the R and C so that capacitor is fully charged or almost fully charged with just half sine. That way you much easier can see what happens as measurements will be more accurate.
Yes of course resistor will be in series with capacitor in order to limit the current and be able to calculate the current by measuring the voltage drop across the resistor.

EEVblog:

--- Quote from: electrodacus on May 05, 2022, 03:10:15 pm ---
--- Quote from: EEVblog on May 05, 2022, 08:06:18 am ---
--- Quote from: electrodacus on May 05, 2022, 04:31:52 am ---2) If capacitors are 1m apart and the switch is 10m from both capacitors the time it takes from the moment the switch is closed to the moment any amount of energy is transferred to the discharged capacitor is the time it takes the electron wave to travel 10m.
This again is a proof that energy transfer from the source (charged capacitor) to the discharged capacitor travels trough wires.

--- End quote ---

If you put the switch at the end of the line then yes it will take the delay of the length of the line to start charging, exactly the same as Derek's original question would if the switch was at the end of the line. No difference at all, so that doesn't prove in any way that the energy flows inside the wire.

--- End quote ---

Yes it proves that since energy is not flowing from the switch to the load but from the source to the load. The position of the switch should not be relevant if the energy from the charged capacitor will not need to travel trough wire.

--- End quote ---

The position of the switch matters, otherwise that would break speed of light causality.
If anyone can't get their head around that then put the switch at a Derek inspired moon length. Flipping the switch at the moon can't instantly make something happen on earth, to do so obviously requires the speed of light to be infinite. This is wacko land.

Naej:

--- Quote from: bsfeechannel on May 06, 2022, 03:22:43 am ---However, equations are not the question, here. Maxwell debunked the hydraulic analogy for the flow of energy based on experimental data. He noticed that a stretch of wire through which a current was flowing would tend to show a spike of voltage if interrupted at the point of the interruption, just like a pipe experiences sudden pressure at the point where a valve has interrupted the flow. However what hinted him that the energy didn't flow like a fluid in a pipe is that if you coil up the wire the voltage increases, while with a coiled up pipe you do not have this effect. Also, if you put a piece of iron inside the wire coil, the voltage will increase even more, but not the pressure for the pipe coil. Electricity flowing in wires affect other wires nearby not connected to each other either by attracting or repelling them if they too are conducting current, or inducing voltages if the currents vary.

--- End quote ---
Yes, this is how the hydraulic analogy is inaccurate. Which is why the word 'analogy' is used: it's very similar, not identical.

--- Quote from: bsfeechannel on May 06, 2022, 03:22:43 am ---Derek repeated the experiment Maxwell observed, only that, instead of opening the switch, he closed it. And he observed that, unlike a pipe, where the energy would never arrive at 1m/c, the electric energy does, and that the hydraulic analogy is what it is, a (should I say poor) analogy, not a description of How Electricity Actually Works.

So the experimental data debunks whatever theory you may have to sustain your misconception.

--- End quote ---
The energy arrives 1m/c where c is the speed of sound in air. For the same reason: opening the valve emits a sound wave, because you're violently compressing/accelerating water.
Just as in the experiment proposed, it's a tiny amount of energy.
Also there's a pressure wave propagating inside the pipe, much like there's a potential wave propagating along the wire (telegrapher's equations also work for the pipe).

snarkysparky:

--- Quote from: electrodacus on May 06, 2022, 05:40:22 am ---
--- Quote from: T3sl4co1l on May 06, 2022, 05:27:58 am ---Why not both?

Stick a 10mF capacitor in series with an AC load and tell me it doesn't transmit energy. :)

Tim


It will not.  You will have a lot of heat loss in the conductors due to repeatably charging and discharging that capacitor.
No energy will get across the dielectric.

--- End quote ---

--- End quote ---
Yes it will.   It's called the displacement current.   

Displacement current is "flowing" anywhere ,  even in an insulator ,  where the electric field is varying with time.

https://en.wikipedia.org/wiki/Displacement_current


electrodacus:

--- Quote from: EEVblog on May 06, 2022, 06:19:25 am ---
The position of the switch matters, otherwise that would break speed of light causality.
If anyone can't get their head around that then put the switch at a Derek inspired moon length. Flipping the switch at the moon can't instantly make something happen on earth, to do so obviously requires the speed of light to be infinite. This is wacko land.

--- End quote ---

Dave, I do understand that.  The point is that source (battery or charged capacitor) is 1m from the lamp/discharged capacitor on earth while switch is at the moon.
The transmission line is just a very long capacitor and it is charged as same potential like the the battery/charged capacitor. So when you connect a multimeter across the open switch at the moon you will not wait the time it takes electron wave propagation from earth to moon to measure the voltage it will be basically instant as the transmission line/capacitor is fully charged.
At the moment you close the switch first electron from one side of the switch will move on the other side collapsing the electric field associated with that electron imbalance. This will continue at the speed of light so if you where able to visualize the electric field line you will see how they collapse starting from the switch on the moon all the way down to earth at basically the speed of light and all that energy contained in the transmission line is radiated as infrared photos in the vacuum of space so ends up as heat.
Up to this point no energy left the battery/charged capacitor and no energy was delivered to bulb/discharged capacitor.

So when switch is closed the transmission line is a long capacitor with significant inductance and resistance.
No energy will flow trough the capacitor / transmission line but it will flow in or out.  So all energy delivered to load flows in the wire and not outside of it unless you count the radiated heat in the form of infrared photons due to wire resistance and it is not even that if you are using a superconductor.

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod