Ken Williams said:
I would like to know in common sense terms what the hell a capacitor does.
is this accurate?:
The simplest way to describe what a capacitor does is as follows:
A capacitor is a device which stores electrical energy in
the form of an electric field.
That's it; that's all there is to it. Any time you have an electric
field between two points/electrodes/whatever, it represents
a certain amount of stored energy, and the "quality" of the
space between those two points which enables this energy
storage is "capacitance."
For a more concrete visualization, imagine it this way. If
I have two flat conductive plates, separated by some distance
(the important thing being that the plates are NOT in contact,
and you can't get a conductive path between them - including
via an arc), then I can put opposite charges on the two plates
(one "+" and one "-"), and those charges will be held there
by the simple fact that opposite charges attract.
But how much charge can you put on the plates? If you remember
that *like* charges repel, you might also think that at some point,
there will be so much "like" charge on a given plate that you can't
force any more on there. Or, more correctly - it will take a little
bit MORE "force" to put this next bit of charge onto that plate than
it did to put the last one on. That "force" is voltage - in other words,
the more voltage (which can be viewed as "electrical pressure") I
have, the more charge I can force onto the plates before they won't
accept any more. The relationship between the amount of charge
you store and the voltage it takes to store that charge, for a given
physical situation, is the "capacitance" of that particular situation.
It is determined by the arrangement and size of the plates, the
properties of the physical material separating them, etc.. The
relationship between charge, capacitance, and voltage is given as
Q = CV or C = Q/V
where C is the capacitance (given in a unit called "farads"), V is
the voltage, and Q is the charge in coulombs.
Clearer?
Bob M.