"--" wrote:
"Floyd L. Davidson" wrote:
"--" wrote:
Strictly speaking, I believe the reactance (part of impedance)
equations apply to any variation in current magnitude. Their appropriate
application does not in any way require reversing the charge.

Exactly.

1) I think one needs to define the term "alternating current" by its
phenomena rather than define it by what applies to "AC". In other
words,
define AC as alternating current -rather than defining AC as "anything
requiring an impedance calculation because of its magnitude variation".

What value does that have? The problem is circuit analysis,

No, rather the problem is that many of the fundamental physical sciences and
most of electrical engineering use the concept, and it is not used merely by
a small corner of circuit analysis. The definition has to work for all the
sciences where it may be used.
E.g., many switches use the "AC as reversing" concept for quenching
contact arcs during switching (as the current passes thru zero as direction
reverses) and the defintion of AC as varying DC falls flat for that purpose.
Install an AC designed switch on a varying DC circuit, and you may well have
a safety switch contacts welded shut. Here, AC DEFINITELY means reversing
direction.

Bad example. That does *not* require a direction reversal. All
it requires is understanding that it is relative to the static
state.

It does happen that the static state in that specific case is
when a polarity reversal takes place, but in the general case it
is not required. In other examples both sides of the switch
might well be at some DC potential, that happens to be equal on
both sides at the time the switch is made, even though there is
no direction reversal.

which requires the division between DC and AC,

I believe the equations are not DC-AC specific - the "AC" term drops to
zero if the change in magnitude drops to zero. Your rationale of using the
equations does not hold up.

Everything concerned with reactance is AC specific. Nothing
concerned with reactance requires a polarity reversal.
Reactance is the essence of the difference between DC and AC,
not some notion of reversing polarity.

AC is defined as:

charge flow that changes direction.

which leaves the calculations for reactance out of the definition.

Which means it is worthless. Reactance *is* the significance.

3) In the definition approach to a phenomena, one deals with the
descriptive term and the phenomena itself and ignores the present
attached

The problem is defining something with no practical value.

We define air, and black holes, and impracticality.

All of which *does* have practical value.

And if memory serves me correctly, the "AC" equations are rigorous, and
apply equally well to your one-voltage DC when the frequerncy drops to zero-
the reactance term of the changing magnitude goes to zero.

That is an hilarious idea! If the magnitude is zero all the way
around... we aren't talking about AC or DC... maybe about
blown breakers or taking a coffee break, but not about current.

And "varying DC" is a contradiction in terms to begin with. Do
we actually need *four* states:

1 -- DC
2 -- Varying DC
3 -- AC
4 -- Steady AC

no, just two - reversing flow direction, and varying magnitude.

Oh? DC doesn't exist? What about "steady AC"? (That's two
exactly equal signals 180 degrees out of phase, combined in that
capacitor which can generate AC mentioned by John Fields,
perhaps???)

Because the reactance equations only apply to varying magnitude, and they do
not apply to reversing direction.

Then why would we be concerned at all about this reversing
direction, and give it a specific name and have a whole separate
field of study for it? Sounds like we need to be concerned with
varying magnitude, *not* with reversing direction. (Which is
what I've been saying...)

As I understood, scienctific method is designed to remove personal views
from science. Thus the definition,must stand alone, and since we can't see
all that is ahead, science has to fall in behind a definition of that
phenomena in pure terms.

imho.......

A nice goal.

----------------

Alternating-direction Current, aka Alternating Current

Except that alternating direction has no significance. Changing
magnitude does. Why bother with alternating-direction at all,
it is just an insignificant, though interesting, part of the
more general case of changing magnitude. All of the same
equations apply.

Direction-specific Current, aka Direct Current.

And if you claim that only alternating direction current is AC,
then you have to have two sets of equations for DC, one for
non-varying magnitude and one for varying magnitude.

That doesn't make a lick of sense.

--
Floyd L. Davidson http://web.newsguy.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)