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Electroboom: How Right IS Veritasium?! Don't Electrons Push Each Other??
electrodacus:
--- Quote from: hamster_nz on July 01, 2022, 09:13:25 pm ---Agreed - they are identical. Now as you state "the energy flows in wires" - try to answer how much energy is flowing in each wire in both pictures.
There are only three values - 0, 1x the energy dissipated by each resistor or 2x the energy dissipated by each resistor. And we both agree that if you assign 0 power to any wire, then that wire can be removed, because it isn't carrying energy.
I can't get a consistent solution to this - one where the energy flowing in each wire doesn't change when I remove the wire in the middle, that is carrying zero energy. Not that I really expect to, because the energy isn't in the wires. If you can help me out with consistent "energy in each wire" numbers I'ld appreciate it.
(I do have a different solution that sits well with me, and solves this correctly and consistently, but it implies that the energy is not in the wires...)
--- End quote ---
Resistors are wires.
You consider that those "wires in the diagram have zero resistance or so small that you are ignoring for the calculation".
If each battery is 10V then voltage drop on each resistor will be 10V valid for both circuit variants as the variants will only make a difference if the circuit was not symmetric so either resistor had different values or battery voltages will have been different.
So the circuit total power dissipation is 20W with 10W dissipated as heat (infrared radiation) on each resistor.
Over 1 second interval 20Ws (20J) worth of energy is transported through wires (resistors are also wires).
20Ws worth of energy is transformed in electromagnetic radiation (in the infrared wavelength so with a broad range of frequency in THz region).
If you consider 10m of very low resistance wire and 1cm resistor (also a wire with much higher resistance) then the low long low resistance wire will radiate orders of magnitude less than the resistor.
The resistor/wire radiates electromagnetic radiation but much slower than it receives due to thermal energy storage. So you may only provide a 1 second pulse of energy but the energy stored in the thermal mass of the wire/resistor will much more slowly be released to ambient as electromagnetic radiation.
electrodacus:
--- Quote from: hamster_nz on July 01, 2022, 09:31:01 pm ---My thinking is that if I remove the upper wire, in one diagram 1x the energy stops flowing, but in the other diagram 2x the energy stops, so if the energy is in the wire, then for one diagram the number must be 1x the other 2x.
Where is that idea flawed? It can be built and bench-tested if desired...
--- End quote ---
Do you agree that no current flows through that wire that you removed ?
If so that wire is useless and removing it will make no change.
hamster_nz:
--- Quote from: electrodacus on July 01, 2022, 09:52:49 pm ---
--- Quote from: hamster_nz on July 01, 2022, 09:31:01 pm ---My thinking is that if I remove the upper wire, in one diagram 1x the energy stops flowing, but in the other diagram 2x the energy stops, so if the energy is in the wire, then for one diagram the number must be 1x the other 2x.
Where is that idea flawed? It can be built and bench-tested if desired...
--- End quote ---
Do you agree that no current flows through that wire that you removed ?
If so that wire is useless and removing it will make no change.
--- End quote ---
Fully agree. But I still cant decide if one unit of energy or two is flowing in the top wire. With the center wire in place it is 1, with it removed it is 2.
But as you say, removing that wire makes no change, so it must be only one or the other..
electrodacus:
--- Quote from: hamster_nz on July 01, 2022, 10:04:38 pm ---
Fully agree. But I still cant decide if one unit of energy or two is flowing in the top wire. With the center wire in place it is 1, with it removed it is 2.
But as you say, removing that wire makes no change, so it must be only one or the other..
--- End quote ---
What flows through the wire are a stream electrons and that will be the definition for electrical current.
The current through that top wire has no reason to change as it will be the same with that center wire in placed or removed.
If we consider that internal DC resistance of the battery is zero (not realistic) then open circuit voltage of the battery will be the same as voltage under load.
Since voltage you will measure between the top and bottom wire will be the voltage of those two batteries in series in my example 20V the current through that 20Ohm of total resistance will be 1A.
At any one moment there are 20W of power dissipated as infrared radiation to the environment and in therms of energy you will need to specify a period like say for 1 second will be 20Ws = 5.55mWh but in 1ms it will be 1000x less so 20mWs = 5.55uWh
hamster_nz:
--- Quote from: electrodacus on July 01, 2022, 10:13:05 pm ---
--- Quote from: hamster_nz on July 01, 2022, 10:04:38 pm ---
Fully agree. But I still cant decide if one unit of energy or two is flowing in the top wire. With the center wire in place it is 1, with it removed it is 2.
But as you say, removing that wire makes no change, so it must be only one or the other..
--- End quote ---
What flows through the wire are a stream electrons and that will be the definition for electrical current.
The current through that top wire has no reason to change as it will be the same with that center wire in placed or removed.
If we consider that internal DC resistance of the battery is zero (not realistic) then open circuit voltage of the battery will be the same as voltage under load.
Since voltage you will measure between the top and bottom wire will be the voltage of those two batteries in series in my example 20V the current through that 20Ohm of total resistance will be 1A.
At any one moment there are 20W of power dissipated as infrared radiation to the environment and in therms of energy you will need to specify a period like say for 1 second will be 20Ws = 5.55mWh but in 1ms it will be 1000x less so 20mWs = 5.55uWh
--- End quote ---
That may all be true, but is 1x or 2x the energy being converted to infrared by a resistor flowing in the top wire in each circuit?
Everybody agrees that both circuits have the same currents and voltages and powers and energy flows.
I would have though it is an easy qn. If energy flows only in wires, how much energy is flowing in the upper wire for both circuits? Because the currents and voltages are consistent, so should the energy...
Isn't it as simple as remover the top wire and see how much the power in the resistors changes?
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