Understanding Capacitor Principles: How Current Flows and Preventing Breakdown

[Bringitondown]

Hi folks,

Just looking for an explanation on capacitor principles.

My understanding:
A capacitor is made from two conductors ( which have the ability to hold charge) separated by an insulator. Therefore current cannot flow between the+ and - plates. Unless unwanted breakdown from excessive voltage values.

If so how can charging current flow through capacitor c1 to the positive plate in c2 in the figure attached.

I am trying to form an understanding of principles here so any advice will be greatly appreciated.

Thanks.

 

[BvU]

Hi biod,

If so how can charging current flow through capacitor c1 to the positive plate in c2 in the figure attached

The current does not flow "through" the capacitor. What happens is that the charge that is pushed on to the top plate of C1 repels the charge on the bottom plate of C1. That charge has nowhere to go but towards C2 where it repels the charge from the bottom plate of C2. By the time the charge on C2 has built up a voltage V2 and the charge on C1 a voltage of V1 and also V1 + V2 = V, the voltage from the battery, charge doesn't flow any more. Current is moving charge, so no current.

 

[meBigGuy]

The current flow is storing energy in the form of an electric field in the dielectric between the plates. The applied voltage causes current to flow at each terminal as an electric field is produced. It looks like current is flowing between the plates, but it is actually producing an electric field. The same current flows back out when the capacitor is discharged.

 

[Bringitondown]

Fantastic responses, thank you so much. Think I've got it just going to do some further reading of the back of your information. Thanks again

 

[jim hardy]

You might enjoy this article
http://amasci.com/emotor/cap1.html

"Science is but language well arranged" and Beatty spends a lot of time exploring ambiguities stemming from 'less than optimal' choices of words.

I have a favorite essay on that subject - http://web.lemoyne.edu/giunta/ea/LAVPREFann.HTML the preface section...
last line:

: "But, after all, the sciences have made progress, because philosophers have applied themselves with more attention to observe, and have communicated to their language that precision and accuracy which they have employed in their observations: In correcting their language they reason better."

old jim

 

[CWatters]

Hi biod,
The current does not flow "through" the capacitor. What happens is that the charge that is pushed on to the top plate of C1 repels the charge on the bottom plate of C1...

Is there a limit on the amount of charge that can be repelled from the bottom plate? Let's say the top plate was made negative so elections are repelled from the bottom plate. Is it possible to repel all the free electrons and what happens then ?

 

[Bringitondown]

Thanks for that Jim, good read.