AC flowing through a cap. What actually happens?

[BrownOut]

But an ammeter that "measures the field" is not measuring the current, it's measuring the field. Read your own writing: "(that) directly measures the field".

That's how current is measured, and has been for a hundred years.

In a vacuum capacitor current does not pass through the vacuum.
Do you have any other example of a current passing through a vacuum?

Sure it does.

We then hypothesized that there was a virtual string across the second set of nails

Speak for yourself. I never made any such hypotheses. First you said there was no string, and now you're saying there is a string. I was correct to not waste any time trying to make any hypotheses. None of this has anything to do with our discussion of current.

BTW just because some people or groups are totally bogus about something (free energy) and you dont fall for it, that doesnt mean everything you dont understand falls within the same class of being bogus.

I understand perfectly. I've made the right call all along.

 

[MrAl]

Hello again,

Ok, since we havent made any progress in the last 200 posts (chuckle) i'll offer up a compromise....

I'll accept that the current in the wire might be real, if you accept that the current through a vacuum capacitor might not be real.
I think that's fair based on everything we discussed. We can then leave it to the future for better proof one way or the other.

If you decide not to accept that compromise, then you must realize that there is no point in discussing this any further anyway.

 

[BrownOut]

Hello again,

Ok, since we havent made any progress in the last 200 posts (chuckle) i'll offer up a compromise....

I'll accept that the current in the wire might be real, if you accept that the current through a vacuum capacitor might not be real.
I think that's fair based on everything we discussed. We can then leave it to the future for better proof one way or the other.

If you decide not to accept that compromise, then you must realize that there is no point in discussing this any further anyway.

I agree. Our failure to reach a consensus stems from our different definitions of current, and there is no path to a conclusive one. I've learned alot during our debate, though I may have seemed predisposed to a singular idea. On to more productive things...

 

[Mr RB]

...
So the current is through the capacitor as it is for a resistor? You can keep a DC in a resistor for any length of time, but not in a capacitor, can you?
...

(I apologise for snipping so much of your reply but it's only this point above that I think requires a response.)

Current is an instantaneous value Ratchit.

I believe electronics guys use a different term for current measured over a period of time.

Maybe you should have chosen a degree that would have empowered you to be more capable in electronics than the degree you did.

 

[Ratchit]

MrRB,

Current is an instantaneous value Ratchit.

Current does have an instantaneous value, a RMS value, and an average value, as does voltage.

I believe electronics guys use a different term for current measured over a period of time.

Yes, they call it the average current.

Maybe you should have chosen a degree that would have empowered you to be more capable in electronics than the degree you did.

I don't agree with your premise. Current is not a difficult quantity to grasp. What is there you don't understand about current?

Ratch

 

[killivolt]

Pictures on the first page is worth a thousand maybe 2 thousand ? I don't know.

AC flowing through a cap. What actually happens? It's the energizer bunny thread it keeps going and going and .........well you know.

 

[ljcox]

The basic difference of opinion we are having is over the definition of current.

Mr Al & Ratchit argue that a real current is flow of charge carriers.

Brownout & I argue that Id is also real - even though no charges flow.

Both of the learned professors showed that Id = Ic where Ic is the conduction current.

One did it for a DC source where Id = Ic = V/R e(-t/RC)

The other for a steady state AC case where

Id = Ic = -C ω V sin ωt

 

[ben7]

Well getting back on topic,

The best way I could think of it is like this:

A [discharged] capacitor when hooked up to a battery will draw current from the battery until it has a full charge. That current looks like a curve over time.

So basically the capacitor is charging and discharging when hooked up to AC source, and the larger the DC inrush current it has, the more AC current it will let flow. And the reason why it happens is the leakage current in the cap will dramatically drop very soon after having DC connected to it.

So to pass a low frequency at for example 1A, we would need a large uF cap.
And to pass a high frequency at 1A, you could use a very low uF cap.

Am I explaining it right? :S
I don't know the technical formulas and such yet so bare with me

-Ben

 

[Ratchit]

ljcox,

Brownout & I argue that Id is also real - even though no charges flow.

No charge flow, no current.

Apparent current is an equivalent current, a current that would exist if the magnetic flux inside the capacitor were produced by a current instead of a changing electric field intensity. It is analogous to the mechanical equivalent of heat. A bowling ball rolling down an alley has kinetic energy (KE). That energy can be expressed in heat energy instead of KE. The moving bowling ball represents virtual heat, even though its temperature has not risen. The apparent heat energy is not really heat, just an equivalent KE. The apparent current represents the equivalent magnetic flux density (B-field), even though the apparent current did not product the B-field. The changing electric field intensity did.

Ratch

 

[Ratchit]

ben7,

Am I explaining it right? :S

No.

Ratch

 

[BrownOut]

ljcox,



No charge flow, no current.

Apparent current is an equivalent current, a current that would exist if the magnetic flux inside the capacitor were produced by a current instead of a changing electric field intensity. It is analogous to the mechanical equivalent of heat. A bowling ball rolling down an alley has kinetic energy (KE). That energy can be expressed in heat energy instead of KE. The moving bowling ball represents virtual heat, even though its temperature has not risen. The apparent heat energy is not really heat, just an equivalent KE. The apparent current represents the equivalent magnetic flux density (B-field), even though the apparent current did not product the B-field. The changing electric field intensity did.

Ratch

Looks like another irrelevant anology to me. The B-field produced by the displacement curernt is real, and the "heat" is some "equilivancy" that isn't real. Real B-field means real current, per Ampere-Maxwell. Really, these false analogies are easy to see through.

 

[MrAl]

Hello again,

Ratch:
Please dont be too hard on Ben, he's just starting out and he is my neighbor

Brownout:
I am not arguing pro or con here, just asking something. Are you arguing that in the wire since the changing E flux creates a changing B field (as per Maxwell-Ampere (1/c)dE/dt term) that this changing B field in turn creates a real current of moving charge in the wire?

 

[BrownOut]

Hello again,
Brownout:
I am not arguing pro or con here, just asking something. Are you arguing that in the wire since the changing E flux creates a changing B field (as per Maxwell-Ampere (1/c)dE/dt term) that this changing B field in turn creates a real current
of moving charge in the wire?

No. I'm saying that Maxwell-Ampere defines current.

 

[BrownOut]

They're probably better off without it. DOH! Wrong thread! why can I no longer remove erroneous posts?

 

[tvtech]

They're probably better off without it. DOH! Wrong thread! why can I no longer remove erroneous posts?

LOL.

Cheers

That's funny. Sorry.

 

[MrAl]

No. I'm saying that Maxwell-Amphere defines current.

Hello again,


What units are you getting on both sides of the Maxwell-Ampere equation?
(ie., units=units)

PS i think you can at least erase the contents and put something like <post erased>.

 

[BrownOut]

Hello again,


What units are you getting on both sides of the Maxwell-Ampere equation?
(ie., units=units)

Is that a serious question? Have you never studied Ampere?

 

[MrAl]

Hello again,

Yes, and yes.

 

[BrownOut]

Then why are you asking? It's in every physics book known to man. ( Hint: The unit is named after it's discoverer )

 

[MrAl]

Hello again,

I just want to make sure im getting the same results as you are. There's lots of units named after someone so that doesnt help yet

Thanks.