Date:         Tue, 11 Jul 2006 00:59:33 -0700
Reply-To:     Robert Fisher <refisher@MCHSI.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Robert Fisher <refisher@MCHSI.COM>
Subject:      Re: cigrette lighter  or silver socket - amp problem with air
              compressor
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
              reply-type=response

Er... I believe he was attempting to *clarify* the concept.

Cya,
Robert

----- Original Message -----
From: "David Beierl" <dbeierl@ATTGLOBAL.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Monday, July 10, 2006 11:58 PM
Subject: Re: cigrette lighter or silver socket - amp problem with air
compressor


> At 08:30 PM 7/10/2006 -0700, BA wrote:
>
> Hmm...may I fiddle with this a little?  I think there are at least a
> few points there that may be a bit confusing.
>
> Lessee...ok.  Electrical circuit is very like a plumbing circuit, but
> mebbe even better to think of a hydraulic circuit, because the
> purpose of each is to do work rather than supply a
> substance.  Hydraulic circuit transmits mechanical work as the
> product of pressure drop and the actual quantity of hydraulic fluid
> that flows through the point where work is being
> extracted.  Electrical is very nicely analogous: it transmits work as
> the product of *potential* drop and the actual quantity of electrons
> that flows through the point where work is being
> extracted.  "Potential" is an electrical word that means, well,
> pressure.  You can see the word itself refers to the
> intensity/fury/projected ability/puissance/potency etc. to imbue each
> electron in the flow with the ability to carry out *that* much work
> by actually pushing on the next in line.  When you get up to a
> pressure drop of 25,000 volts or so the shove is so hard that if
> there's a gap in the wire terminated with a one-inch ball at each end
> the electrons will leap across an inch of dry air to escape the
> crowding from the electrons piling up inside the ball.  Even with
> that force electrons are so small that it takes a great many to
> accomplish anything noticeable on our scale, which is why we don't
> die every time we scuff our feet on the carpet.  ONE AMPERE is the
> flow rate that will suffice to accomplish ONE WATT of work at a
> pressure drop of ONE VOLT, and the number of the Holy COULOMB of
> Antioch is verily the same [ok, they're not the same, but from this
> distance they might as well be, just the same as how all those
> Left-Coast people think I live in New York City and I'm equally
> convinced the Angelinos and the Albucolloquians wave to each other in
> the street every morning]  as Avogadro's number which was once
> tattooed on your skull somewhere in high-school chemistry.  Roughly
> 600 000 000 000 000 000 000 000 New Yorkers storming the subway every
> second, so heedless they warm the place up from rubbing against
> it.  And the amount of obsticality or RESISTANCE lying about that
> will extract ONE WATT of power every second from ONE AMPERE (which is
> 6x10^23 electrons every second) under the maddening goad of ONE VOLT
> of pressure drop is -- ONE OHM.
>
> Oh yeah...capacitor is like a section of pipe with a rubber diaphragm
> blocking the middle.  Shove fluid in from either direction and it
> gets harder and harder as you stretch the diaphragm one way or
> t'other, and .  You can store work that way, by pressing against the
> springiness of the capacitor.  You can also transmit work continously
> right through it even though it blocks any continuous flow.  I'll
> take that hall pass, Tonstant Weader And if you need to store more
> work than you can ram into a big capacitor, or maybe you need it to
> come already stored...arrange to hang onto those electrons chemically
> instead of just by overt shoving and you have invented a PRIMARY
> (comes already filled with all the work it's going to be able to
> supply) or SECONDARY (BYO electronic seltzer bottle and CHARGE IT
> whenever it runs low) BATTERY.  Which looks amazingly like a big
> capacitor if you squint just so; and a very very large capacitor
> looks remarkably like a rather small battery.  A ONE FARAD capacitor
> will accommodate ONE COULOMB of electrons AKA ONE Amp-SECOND if you
> apply ONE VOLT of pressure across it. And to the eye-popped disbelief
> of those of us old enough to know why the electron has a cross on his
> tail (see NOTE below), they're actually making capacitors lately the
> size of a New Jersey blueberry that have a capacity of ONE FARAD and
> voltage rating of a few volts.  If there was an article of faith in
> my generation I believe it was that we would never get close enough
> to a one-farad capacitor to see the whole building at once...'stonishing.
>
> [Note:] Answer: Ben Franklin guessed -- wrong.  And so for hundreds
> of years people quite knowingly did all their electrical calculations
> upside-down and backwards serene in the knowledge that the answers
> worked perfectly well.  Around ?1975? some bright spark struck a blow
> for correctness and got the tech schools to teach negative current
> instead of positive current to the new crop of baby techs.  And now
> any time technicians want to talk electricity with each other, they
> have to agree ahead of time whether to talk positive or negative
> current.  And the answers are the same as before, except when someone
> accidentally shifts midstream to whatever form they growed up
> with.  I'm sure someone must be very proud.
>
> And if you like this little story I'll try to do another piece of it
> in a week or two.  But in fact if you wanted to stretch a bit and
> were bored with crosswords, it's pretty remarkable how far you could
> get with those two paragraphs, a suitable stick to scribble with and
> a month lease on a deserted beach.  Preferably one where the tide
> didn't erase it every night.
>
>
>>Capacitance is a well that's somewhere along the pipe.  For a while,
>>the water fills the well and doesn't continue along the pipe.  But if
>>you fill up the well and keep adding water, then the water simply
>>keeps on flowing in the pipe.  If you increase the pressure, the water
>>doesn't fall into the well but just goes straight through the pipe
>>(that's a blown capacitor!).
>>
>>A resistance is a narrowing of the pipe.  (Or, a widening of the pipe
>>which would provide less resistance rather than more).
>>
>>Amperage is how much water is flowing through the pipe.
>>
>>Voltage is how much pressure there is on an end of pipe caused by the
>>pressure of the water on that end of the pipe.
>>
>>Batteries and generators are water pumps.
>>
>>Any more that I've missed out?
>>
>>
>>
>>If you don't understand it using the plumbing analogy, then there's
>>another lovely analogy.  It's in the book "There Are No Electrons:
>>Electronics for Earthlings"  ISBN 0962781592.
>>
>>
>>B&S
>>'87 Westy 'Esmerelda Blanc'
>>SoCal
>
> --
> David Beierl - Providence RI USA -- http://pws.prserv.net/synergy/Vanagon/
> '84 Westy "Dutiful Passage," '85 GL "Poor Relation"