"daestrom" wrote:
"Floyd L. Davidson" wrote in message
...
John Fields wrote:
On Sun, 12 Jun 2005 14:00:23 -0800, (Floyd L.
Davidson) wrote:
'Alternating' means both magnitude and direction vary over time. A current
that varies in magnitude but not direction is not 'alternating'.
Then you'll have a very difficult time explaining now a
transistor amplifier works if it uses AC coupling that involves
capacitors.
Since the voltage varies, the current will also, but the _direction_
in which the electrons are travelling will never change.
If it varies, it's AC.
Only by your apparent definition. But your definition does not agree with
the established industry.
Which industry? You can't do AC circuit analysis with any other
definition.
If there is such a think as "varying DC", connect a load to
it... through a capacitor. Now, how do you describe the effect
that load has on your "varying DC". The load see's *only* AC,
even according to your definition. That AC came from somewhere,
and it certainly was not generated by the capacitor.
By adding a capacitor in series, you have altered the circuit. The
Capacitors don't generate voltage or current. The circuit
alteration merely demonstrates that the voltage and current on
one side meets all of your requirements, while the identical
charge flow on the other side does not, which indicates a flaw
in your specification.
capacitor filters out the DC component of a the original varying DC voltage
applied.
Yes, which leaves the AC that was there all along. It's AC
after, and it was AC before. If you do circuit analysis the
treatment is exactly the same on both sides of the capacitor.
The capacitor has a varying DC voltage across it, but it never
changes polarity (you can use an electrolytic capacitor that is polarity
sensitive without damage).
Exactly. Yet there *is* current through the capacitor, which
only passes AC. That AC current isn't generated inside that
capacitor. It comes out one side, so it *had* to be coming in
the other side.
The current through the resulting series circuit *does* alternate in
magnitude and *direction*, even though the voltage applied to the circuit
varies in magnitude only. So yes, the 'AC came from somewhere'. But that
doesn't mean the applied voltage is AC. Such logic is flawed. There is no
'law of conservation of AC' that says it can't be 'generated by the
capacitor'.
That's hilarious. DC applied to a capacitor generates AC????
I don't think so.
That's because AC is *not* defined by any change in direction,
but only by a rate of movement change.
Repeating yourself doesn't make you correct.
Won't help your point either. And it makes no difference how many
places you find it ill defined either.
--
Floyd L. Davidson http://web.newsguy.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)