flipper wrote:
On Fri, 23 Jul 2010 00:12:50 -0400, ehsjr
wrote:


flipper wrote:

On Thu, 22 Jul 2010 13:43:51 -0400, ehsjr
wrote:



Jim Thompson wrote:


On Thu, 22 Jul 2010 01:40:54 -0500, flipper wrote:




On Wed, 21 Jul 2010 22:45:33 -0400, ehsjr
wrote:


[snip]



Well, I don't see any inconsistancy in putting "stuff" in at
one rate, and getting that "stuff" out at another, whether it's
water into bottles, cookies into bags, electrons into conductors,
whatever. You get the same amount of "stuff" out as you put in
(assuming you empty the container), but the time taken to do it
is different.

That only applies if your method of getting and putting is lossless
but the general case in electronics is 100%.




Ed



"stuff" is the source of the error.

...Jim Thompson

Exactly. A coulomb is massless. It is not a fixed physical thing


An electrostatic field is massless. Are you trying to suggest an
electrostatic field is not 'real'?



that occupies some particular volume,


In reality it does.

Nope. I guess I didn't make my point clear.
You can charge 2 different size (physical volume)
caps with a coulomb. There is no particular volume
associated with "a coulomb".


I don't understand what you are trying to get at.

Are you of the opinion that there is one particular volume,
and one particular volume only, that a 1 coulomb charge
will occupy? If so, what is that volume?
If not, then you and I have no disagreement on the point.

To go further. A coulomb is a numerical result of a mathematical
operation, not a physical object. There is no physical object
that is an "ampere second". A coulomb is massless, and volumeless.
The puzzle misdirection appeared to be treating the coulomb as an
object that could be divided by dividing that coulomb's container.



Area and spacing, which define a volume, the dielectric of the volume
and the applied volts determine the coulombs. It's not an 'arbitrary'
thing and, in that sense, yes it is 'fixed' (by the particulars).
Otherwise one would not be able to write an equation for it.

It's even more the case when simply alternating between parallel or
series connections as none of their parameters change, not even V
(hence Q), and that's about as 'fixed' as one can get.


which seems to be the
misconception at the heart of the so called puzzle.


If you are referring to the, so called, 'missing coulomb' there isn't
one.

Correct, there is no missing coulomb. I've already said that,
earlier in the discussion.


Ok. So I threaded back and, unless I misunderstood, you seem to be
suggesting there is some unexplained 'difference' between whatever you
deem a 'real' 1F capacitor and two 2s in series, despite their
identical behavior, so that two 2s in series are "not a 1F cap" and 1F
"doesn't matter."

Not what I was suggesting.
In the puzzle the 2 coulombs is a number that tells you how much
current got stuffed into a container and how long the "stuffing"
took. Magically dividing the container into two containers
(or N containers) does not change the amount of current got
stuffed in, nor the amount of time it took to do that stuffing.



There's no need for mysterious 'differences' as, assuming all else is
equal, a single 1F, two 2s in series, four 4s in series, eight 8s in
series, and so on (although equal values are not required, just that
the resulting series comes to 1F), are black box indistinguishable. At
1V overall they'll each and every one have 1 coulomb because they all
have the exact same charging current go through.


The puzzle's magic division creates the "mysterious differences"
(it results in Vcap = V/N for each cap), hiding the fact that
total ampere seconds is the same.

You may have missed the context of the whole starting from
the beginning, when a "puzzle" (which wasn't a puzzle at all) was
presented. And I don't think it matters - the puzzle was just "mental
gymnastics" that caused confusion instead of making a point, in my
opinion. Your paragraph above shows you understand the principle,
so the puzzle is irrelevant. And the op clarified his meaning:
"My point all along is that, in actual circuit design, the generalism
"charge is conserved" is dangerous, given that "charge" is
ampere-seconds that you can actually measure and use." His "puzzle"
was misdirection to show that a coulomb was somehow lost. No
coulomb was lost.

Perhaps what I've posted isn't clear to you, but if you
think that no coulomb was lost in the puzzle, and that a
coulomb of charge does not require one and only one specific
volume, then we're in agreement.

Ed






Ed

snip