W5DXP wrote:
wrote:
It is instantaneous voltages which make standing waves.
That's a no-brainer.
It is instantaneous signals which cause distortion in diode
demodulators.
Please define "instantaneous" for us. I suspect it cannot be what
happens in a dt=0 time slot.
With a time varying voltage, for each time t there is a particular
value of voltage. This voltage can be called the instantaneous voltage
to make it clear that it is not the average or RMS or peak or any
of the other voltages which may be of interest with regards to the
signal. Hence the notation v(t) representing the voltage at any
time t.
It is instantaneous voltages and currents which
are added and subtracted in Bird wattmeters.
But the result is rectified and the maximum value is stored on
a capacitor. By definition, a capacitor cannot accept an instantaneous
value of voltage. If it could, it would be called an inductor. :-)
None the less, the original additions and subtractions of voltages
and currents must be done with the instantaneous values for the
proper results to be obtained.
But I notice an instantaneous willingness to reject the value of
instantaneous power.
Please prove that the human brain is capable of instantaneous willingness. :-)
If you will accept proof by example, then simply re-read some of your
posts.
But to reject instantaneous power in a consistent manner, you need to
explain why you do not also reject instantaneous velocity, acceleration,
current, flow or any of the many other interesting things which are a
derivative with respect to time.
Some things logically have an instantaneous value, e.g. voltage. Other
instantaneous values do not seem to be related to reality. Let me use
your mind-f__king techniques on you. So you are saying that all instantaneous
values appearing in any math model anywhere have an associated existence
in reality.
Absolutely not. But I have asked that if you wish to contend that
instantaneous power is of no use while instantaneous current is, that
some rationale be provided. The previous arguments were that it made
no sense because when dt was 0, there was no power. This seemed a weak
argument since a similar argument could be made for the other
instantaneous
value which do seem to be accepted.
Assertion A:
"In a shorted ideal transmission line which has reached steady state,
no energy can cross a voltage or current minimum because
p(t) = v(t) * i(t) and at a voltage or current minimum, the voltage
or current is always zero, so the power is always zero, so there is
no energy flow across a voltage or current minimum."
Assertion B: Since the universe is about 15 billion years older than
our solar system, transmission lines have probably been doing their
thing for billions of years longer than your above statement has existed.
Does this non-sequitor mean that you accept Assertion A and wish to
deflect the discussion?
This conclusion contradicts a commonly held belief:
Yes, and is therefore probably as wrong as can be.
Perhaps, but I observe that you have not yet pointed out the flaw.
Were you to find the flaw in the logic, I would willingly accept
it as false. Merely that the result disagrees with Belief B is
not, by itself, a flaw.
There is absolutely
nothing in physics that prohibits energy from flowing across an area
where power is zero.
I had always understood that power was defined as the rate of energy
flow. If the power is zero, then by definition, there is no flow.
Perhaps your definition of power is different and we should resolve
that before proceeding.
Belief B:
"that in steady-state, energy is flowing along the transmission line
to the end where it is reflected and travels back to the beginning."
Please present a model of how standing waves are possible without forward
waves and reflected waves in a single-source, single feedline, single load
system.
Well, as you agreed near the start of this post (with your statement
"That's a no brainer), it is voltage waves which produce standing waves,
not waves of energy. So Assertion A is not in conflict at all with
standing waves.
Until you do that, you are just, IMHO, blowing smoke.
It is certainly possible that I have made an error in Assertion A. I
observe that you have not yet located that error. But Assertion A
is fairly short and based on the most basic of concepts. It should
be easy to locate and describe the error, if one exists.
Unless you can find an error in the logic of Assertion A, it would
seem reasonable that you re-assess your acceptance of Belief B.
The error in assertion A is that EM light waves cause power nulls
without having any effect on each other whatsoever. And that's exactly
what happens in a transmission line.
Please go through each of the steps of Assertion A and describe the
first one which is in error and why.
Assertion A caused me to reject Belief B and the world did not
collapse:
When you reject the primacy of consciousness in favor of the primacy
of existence, you will understand why your thoughts don't effect reality.
Your thoughts also do not affect much of reality. What happens when you
God-like gurus disagree? - Close to nothing!
This, of course, would not assist with the understanding of the nature
of
'reflected' power.
When you get through with that, consider what happens if time doesn't
really exist and is simply a model of change invented by the human mind.
What happens when you divorce change from the rotation of the earth?
Nor would this.
....Keith