Re: "Electric current" does not mean "electron flow"

[William Beaty <billb@ESKIMO.COM>]

On Mon, 22 Apr 2002, Tim O'Donnell wrote:

> So outside of the battery, do electrons flow (except if one
> is running an electrolytic cell to do metal plating)?

Yes, but not if one is recharging a battery, or running a neon bulb or
neon sign, or restarting a heart with a defibrillator, or trying to
understand how nerves work, or operating a HeNe laser, or a humidity
sensor, or electromagnetic liquid sodium pump, or mercury tilt switch (in
liquid metals the positive ions are movable, and they do flow.)  Any fluid
conductor will contain movable charged particles of both polarities, and
they flow in opposite directions during an electric current.  But these
are details which get in the way of the "circuit" concept.

An electric circuit is analogous to a leather belt which is wrapped around
some pulleys.  When one pulley is forced to turn, the whole belt turns.
Or in other words, forcing the belt to turn will inject energy into the
whole belt all at once.  If the belt extends for miles, then it can be
used to transmit mechanical energy across long distances.  All this is
also true of electric circuits, but in that case the leather belt is
replaced by a "hydraulic fluid" made of charged particles rather than
protein molecules.

In my opinion the reason why most people don't understand electric
circuits is that Reductionism has run amok.  The proper Reductionist
process is to take things apart, understand the parts, then put them back
together and, by studying their interactions, understand the original
problem.  Yet with circuits we have taken the Electricity apart into its
component particles, understood the particles, but for some reason we
refuse to look at intereacting groups of particles, or to put Electricity
back together and once again understand it as a moving "fluid" which
exists inside of conductive materials.

This is silly, it's like insisting that water is "just a property" of H2O
molecules, while denying the existence of liquid water which can be
carried around in buckets.


> Inside
> electrochemical cell ions flow? What about solar cells and
> piezoelectric devices - are electrons involved here or is it
> some other charged particle?

A rule of thumb:  if it looks silvery, then it's an electron conductor.

In p-type semiconductors (and in some metals) the moving particles are
actually empty pockets in a crystalline grid made of trapped electrons.
The electric current in that case is still an electron current, but as the
"hole" moves along, it is a DIFFERENT electron which moves backwards each
time the hole moves forwards.

Imagine a row of wooden beads on an Abacus.  You can't move the beads
unless there is an empty space, and as you flick each successive bead to
the right, the empty space moves to the left. The beads (electrons) are
the physical objects which move, yet it makes sense to analyze this in
terms of holes or "missing beads" which move backwards. (This is the
"classical physics" view. I'm not sure if the Quantum view contradicts
it.)

I forgot about piezo devices and ceramic capacitors.  They're weird too.
They conduct because the trapped dipoles can rotate or stretch.  Imagine
that they're full of movable electrons, but each electron is tied to an
atom by a short rubber band.

We can eliminate all these complexities by talking about a "first
approxiamation" electric circuit:  a circuit where all the movable charges
have the same polarity.  Since Conventional Current is positive, the
moving charges in an idealized circuit are also positive.

I suspect that many people reject this viewpoint, and insist that
electrons must be the particles which flow.  This is the fallacy
"electricity is made of electrons."  But electrons are REAL, just like
positive ions are real.  To eliminate the confusing complexities, replace
all the real charged particles with positive particles made purely out of
"Conventional Charge."   Inside the wires is flowing "positive
electricity"  Inside the batteries it's the same.

Here's a dirty little secret: Some common metals are hole conductors as
well as electron conductors. If I recall, aluminum is one example.  FOr
those who insist that elctric current is REALLY a flow of electrons, well
they'd better stick to copper wires and never use aluminum.

One final note: positive conductors do exist.  During an electric current
in frozen water, the normal ions are locked into the crystal, and only the
+H ions can flow...  and a +H ion is a bare proton.  Ice is a "proton
conductor".  Some types of exotic plastic conductors and ceramic
conductors are also Proton Conductors.


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