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Veritasium "How Electricity Actually Works"

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hamster_nz:

--- Quote from: electrodacus on May 01, 2022, 09:31:54 pm ---
--- Quote from: rfeecs on May 01, 2022, 09:14:33 pm ---I disagree.   |O

I wonder how you think radios work.  By energy storage I suppose.

--- End quote ---

Have you properly read my replay ?
A constant electric field will not be detectable by a radio.
A radio works by charging and discharging energy. But the current discussion is much simpler than that.

The circuit simplifies to charging an empty capacitor with a charged capacitor.  If you disagree with the fact that this all that is two parallel capacitors (simplified) then let me know where do you think the omission is.

--- End quote ---

Is what you are saying "If we pick a simplified model, it simplifies to this simple model, that doesn't explain the details of the physical results, but the model agrees with the model, so the model is good".

I'm wait for the "I'll add in ESR resistors and parasitic inductance to take my first-order approximation to a second order approximation, so we get virtual coils and resistors along with the virtual capacitors I've added because my model demands it, not because there are actual coils and capacitors in the experimental apparatus."


Naej:

--- Quote from: rfeecs on May 01, 2022, 08:15:54 pm ---I don't think he adequately debunks the idea that charges gain potential energy (V) and then that potential energy is converted to kinetic energy.  The P=IV model.

He doesn't mention potential energy, just kinetic energy.  He argues that the electrons drift too slowly to carry the energy.

But the (retarded) potential moves at the speed of light.

I imagine he didn't want to mention potential because it introduces another concept that might be complicated to explain.

--- End quote ---
Electron's potential energy is converted into heat in a resistor.
And he didn't debunk it because it is true.

rfeecs:

--- Quote from: Naej on May 01, 2022, 11:53:50 pm ---
--- Quote from: rfeecs on May 01, 2022, 08:15:54 pm ---I don't think he adequately debunks the idea that charges gain potential energy (V) and then that potential energy is converted to kinetic energy.  The P=IV model.

He doesn't mention potential energy, just kinetic energy.  He argues that the electrons drift too slowly to carry the energy.

But the (retarded) potential moves at the speed of light.

I imagine he didn't want to mention potential because it introduces another concept that might be complicated to explain.

--- End quote ---
Electron's potential energy is converted into heat in a resistor.
And he didn't debunk it because it is true.

--- End quote ---

Yes, of course it's true.  But his "misconception number 1" is "electrons carry energy from battery to bulb".  He tries to prove this without mentioning potential energy which seems to be part of the most common explanation.

electrodacus:

--- Quote from: rfeecs on May 01, 2022, 10:16:34 pm ---I have already done that.  I have said there is radiation.  You say there isn't.  Enough said.

The simulation shows what happens.

If I wanted to model it, I would start where the battery/switch is connected to two wires.  These wires form an antenna, or an odd looking transmission line.  They can be thought of as a skinny bi-cone antenna.  The infinite bi-cone looks like a transmission line and has constant impedance.  It has spherical symmetry and the wave propagates out spherically.  In this case, the wires are not conical but straight, but the propagation is approximately spherical and the impedance will change along the line but levels off to a slow increase in impedance.

When the switch closes, there is a transient voltage change, as in a Heaviside step function.  This transient is what starts the energy propagating out in all directions, roughly spherically.

After a period of time, the wave front hits the top pair of wires.  Now we have another antenna / transmission line.  The electric field across the load will cause a current and voltage wave to propagate along this line in a similar manner as the source antenna.  Clearly the signal is much smaller because the field has spread out spherically. 

The two antennae are clearly coupled and form another set of transmission lines, the twin line that has been often mentioned.  So to properly model this I would consider these to be coupled lines.  The odd mode impedance of the twin line is well known.  The even mode impedance will be formed by the bi-cone type lines.

Yes, this model is ridiculously more complicated that your capacitor model.  But it can model the fact that the lower pair of wires initially have a lower current than the upper pair of wires and give the correct current for both wires.

Your model cannot do this.

--- End quote ---

We are discussing about a field and you mention radiation. The infrared radiation for example from a lamp or resistor or from battery is not what transfers the energy from battery to lamp.


Do you agree that battery (or charged capacitor) is the only energy source in that example ?
If you do then just move the switch far from the battery and lamp/load then see what is the time required for the lamp to see any current.
You can not claim that energy comes from the switch if you agreed that battery/charged capacitor is the only source.

When the switch closes it just connects one of the plate of the charged capacitor to a discharged capacitor (transmission line).
There is no electric field before closing the switch and first electrons will move in to the wire or out of the wire (depending witch plate you connected) and just because of that you will start to have an electric field.

Here is the super simplified example

  ________________ common plate
  +++++++

  _______/  ________
  -----------


This simplified example of Derek's experiment.
Those are real capacitors so the plates have both resistance and inductance. Capacitor on the left is the charged one while the one on the right is discharged.
What do you think happens when you close the switch ?

rfeecs:

--- Quote from: electrodacus on May 02, 2022, 12:32:28 am ---What do you think happens when you close the switch ?

--- End quote ---

 :horse:

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