Re: Can a capacitor let DC current through?

On 8/21/07 8:42 PM, in article pan.2007.08.22.03.42.26.0@xxxxxxxxxxx,
"Nobody" <nobody@xxxxxxxxxxx> wrote:

On Tue, 21 Aug 2007 19:31:19 +0100, Anonymous. wrote:

Capacitors block DC voltage. AC signals appear to pass through
capacitors,
but they don't actually do that.

Correct.

It's simple electrostatics.

An electron arriving on one plate of (assumed vacuum dielectric)
will repel another from the opposite plate.

An electron pulled off one plate will attract an electron onto
the other.

Pulling and pushing in this way is the essence of AC.

The current doesn't actually flow through, but because the net effect on both
sides is the same, the current appears to flow through!

You can say the same thing about a length of wire. The electrons which
flow into one end aren't the same ones which flow out the other end,
unless the current is DC and you are prepared to wait a long time.

When it comes to AC, the question of whether a current flows *through* a
component is the same whether that component is a capacitor or a resistor.

An alternating current either flows "through" both, or it flows through
neither, or you are arbitrarily changing the definition of "through".


A resistor has no dielectric barrier. A capacitor does.

Why do you believe "An alternating current either flows "through" both, or
it flows through neither...?"

.

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