Well in "Standard Handbook for Electrical Engineers" we can read:The simple concept of a current being charge carriers flowing in a conductor or in a beam (eg. in a CRT) has served us well for 200 years but it MAY need to be revised.
I hope i've made this all clear but if you have any more comments please feel free to note them here even if you dont agree with something here.
Well in "Standard Handbook for Electrical Engineers" we can read:
”Metals are conductors for current, but nonconductors for the flow of energy, while dielectrics are good conductors for the flow of energy.
MrAl,
Quite a presentation, but I prefer something more basic. First of all, current is not a concept. It is a defined quantity of moving charge carriers. If you think of it as a concept, then every quantity would be a concept, and the word would have no meaning. Charges like to flow along conduction paths. What is really fundamental is that current will exist through a component if a conduction path exists through it (like in resistors and inductors), but not if no path exists (capacitor). One can measure a current on both sides of a capacitor and conclude that charge is flowing through the capacitor. But in reality, charge only appears to flow through the capacitor. The dielectric (especially a vacuum) stops the charge flow cold, and charges can only accumulate, deplete, and separate on the plates. As an example, one can measure simultaneously the current in the primary and secondary of a transformer, and conclude that some current is transferring from the primary to the secondary. But we all know that the primary and secondary are really isolated.
As far as I can determine, displacement current is pretend, apparent, artificial, mathematical, and not real. It is an equivalance to the changing electromagnetic fields that occur within a capacitor when its energy storage level (voltage or charge imbalance) is changing. That is why it mirrors the external current. The fact that Maxwell used that concept (a field to current equivalance) to predict electromagnetic radiation does not change that fact. I know of no reason to worry about displacement current except when studying the internals of a capacitor with respect to Maxwell's equations. Circuit analysis from a macro viewpoint seems to get along just fine by defining the external characteristics of a capacitor as a storage element.
Hopefully, the professor will show up soon to set us all straight.
Jony130,
Energy is transferred anytime charge carriers move, whether by conductors or dielectrics. A resistor connected by low resistance wires to a voltage source will demonstrate that those conductors do a good job of transferring electrical energy. Much better than a string of capacitors (dielectrics) connecting the resistor to its voltage source.
Ratch
The basic point I was trying to make, is that no one knows what the “Theory of everything” will reveal.The leaves in the water tells us that there is something there that is actually happening and something else there that is not only going along for the ride, it's masking the truth behind what is really happening physically. The difference is, in a circuits theory class you might be able to teach that "The leaves are moving and we can see that is true, so that's the answer to what is happening. The leaves move somehow because of their own power".
But in a physics class, you'd want to dig deeper and show that the water is what is really moving the leaves. .
This is essentially my point.
Do you remember qtommer? The OP.
His question rang a bell. It was about this explanation coming from the original (longer) articler posted many many years ago Messing Around Activity 2: Capacitors
The basic point I was trying to make, is that no one knows what the “Theory of everything” will reveal.
Obviously the theoretical physicists who are at the forefront of physics will have a better idea of where it is going than the rest of us, but I suggest that even they don’t know with any certainty.
Brownout & I have both shown that Id = Ic as have at least 2 of the lectures that were posted.One thing i did not do yet and that is go into the numbers behind the theories. If the numbers dont work out, that's going to look very bad for displacement current theory.
Brownout & I have both shown that Id = Ic as have at least 2 of the lectures that were posted.
One showed that Ic = 1.2 e^(-t/RC) & Id = 1.2 e^(-t/RC). So what numbers do you need to play with?
This is one reason why charge can not pass through the capacitor, because it would not allow charge to deplete on one side and build up on the other side.
Does this make sense to you or no?
I have never said that charge does pass through the vacuum.
You are hooked on the assumption that current has to be a flow of charge carriers.
I'm saying that since we don't have the full story (ie. the Theory of every thing) then there MAY be an alternative definition.
That's all I'm saying. I don't know the answer, and as far as I know, neither do the experts in theoretical physics.
I'm saying that since we don't have the full story (ie. the Theory of every thing) then there MAY be an alternative definition.
That's all I'm saying. I don't know the answer, and as far as I know, neither do the experts in theoretical physics.
Plate charge is irrelevant, as is anything that happens inside an electronic component.
Current is clearly demonstrated from the OUTSIDE of the component, whenever the component has 2 legs and 1 amp is going in legA and 1 amp comes out legB. That is 1 amp of current regardless of whatever type the component is or how it's insides are constructed.
To Mr Al- Your argument (that I infer from your egg analogies) is that if the same electron cannot travel all the way through (you used the word "conduction") then it does not qualify as current. So since electron A goes in the cap and electron Z comes out the other side, that is not "current"?
Then what about this case, given a long wire, and high frequency AC, then electrons ABC will go in one end of the wire and electrons XYZ come out the other end. Since the speed of electron flow is known you can easily demonstrate with an AC current of reasonably high frequency that any particular electron cannot come out the other end of the long wire, they just go in and out with the AC. That is exactly the same end result as what happens in the capacitor example.
Are you now going to say that long wire does NOT have AC current going through it?
I propose that it does. In any situation where there are 2 legs and 1 amp goes in and 1 amp comes out there is 1 amp of CURRENT through the mystery device. What happens inside is largely irrelevant.
(edit) Mr Al- Having just seen your quote of Prof Viken, I think that is a PERFECT example of exactly why the concept of "current through" is so vital and needs to be respected. In an attempt to manage electron behaviour specifics his communication of standard electronics terms is compromised to the point of disfunction. It doesn't matter what an electron is doing on a plate. It does REALLY matter that there is a through current that can be measured, calculated and relied upon in actual use of the component. I thank you and the professor for proving my case.
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