what happens to reflected energy ?
 

On Jul 5, 9:57*pm, Cecil Moore wrote:
On Jul 5, 7:44*pm, Keith Dysart wrote:

When, exactly, does the EM wave cease to exist?

I don't know exactly but it will be when DC steady-state has been
achieved, i.e. when electrons are no longer being accelerated or
decelerated.

More evasion. So are now saying there may indeed be an EM wave
present with DC? Even with DC, the electrons are not moving with
constant velocity but hop from atom to atom. Seems like
acceleration and deceleration to me.

....Keith

what happens to reflected energy ?
 

On Jul 5, 10:06*pm, Cecil Moore wrote:
On Jul 5, 8:01*pm, Keith Dysart wrote:

Map this to conservation of energy...
Current is to power as charge is to energy.
The relationship and utility is the same.

So now you are pushing a conservation of current principle as well as
a conservation of power principle? You can *destroy* the current and
power with the flip of a switch. Can you destroy charge and energy?
Good Grief!

Maybe you should just start with Kirchoff's current law and understand
what it says before following my suggestion to compare it with the
conservation of energy law.

You seem to have forgotten what you almost certainly once knew.

Google will provide many adequate explanations.

....Keith

what happens to reflected energy ?
 

"Keith Dysart" wrote
...
On Jul 5, 9:57 pm, Cecil Moore wrote:
On Jul 5, 7:44 pm, Keith Dysart wrote:

When, exactly, does the EM wave cease to exist?

I don't know exactly but it will be when DC steady-state has been
achieved, i.e. when electrons are no longer being accelerated or
decelerated.

More evasion. So are now saying there may indeed be an EM wave
present with DC?

Not EM but the electric wave.
In the free electron laser (halbach array) is DC and waves are produced.

Even with DC, the electrons are not moving with
constant velocity but hop from atom to atom. Seems like
acceleration and deceleration to me.

If the electron beam is periodically deflected the current is DC but the all
works like the dipole.
S*

what happens to reflected energy ?
 

"Cecil Moore" wrote
...

If electrons (carriers) are not being accelerated and/or decelerated,
i.e. if DC steady-state exists, then there are no EM waves.

You do not read my posts.

In the free electron laser the DC steady-state exists and there are electric
waves.
"If the electron beam is periodically deflected the current is DC but the
all
works like the dipole."
S*

what happens to reflected energy ?
 

"K1TTT" wrote
...
On Jul 5, 5:14 pm, "Szczepan Bialek" wrote:

Is is trouble with understanding that the all scientists work on plasma?
Only students are in the solid aether. But they simply do not know that
the
famous equations describes such.
Vectors describes the motions of something. Students should not be told
what
it is. Because the goal is math (field method) teaching.

its too hot for this, i'm going for a swim... maybe some nice
longitudinal waves in the water will make me feel better.

Next time look at water waves with the Stokes eyes:
http://en.wikipedia.org/wiki/Stokes_drift

They are more longitudinal than transversal. They transport the mass and the
energy.
S*

what happens to reflected energy ?
 

On Jul 6, 2:02*am, "Szczepan Bialek" wrote:
"If the electron beam is periodically deflected the current is DC but the
all works like the dipole."

I'm afraid "periodically deflected" violates the definition of steady-
state.
--
73, Cecil, w5dxp.com

what happens to reflected energy ?
 

"Cecil Moore" wrote
...
On Jul 6, 2:02 am, "Szczepan Bialek" wrote:
"If the electron beam is periodically deflected the current is DC but the
all works like the dipole."

I'm afraid "periodically deflected" violates the definition of steady-
state.

In AC coulombs/s in one direction is not const In the DC is.
In this sense in the free electronn laser is DC.
S*

what happens to reflected energy ?
 

On Mon, 5 Jul 2010 17:29:49 -0700 (PDT), lu6etj
wrote:

what I do not know is how measure A and
B oscillator to distinguish each other... :D

I gave you that solution: multiply them. Very simple exercise
available to anyone with sufficient bench equipment. Skip the quotes
of undergraduate scribblers with little imagination that shrug their
shoulders at their own failure.

Humorous note: Richard Feynman do not share your dislike for
analogies he compare corks in water with charged objects fields :)

Feynman was a humorous fellow, but you are using undergrad texts
instead of his - why?

As I've already offered, drop all the frills and adornment and tell me
what scale the source of your 80M problem exists at:
1. Subatomic,
2. Atomic,
3. Molecular.

73's
Richard Clark, KB7QHC

what happens to reflected energy ?
 

On 6 jul, 16:24, Richard Clark wrote:
On Mon, 5 Jul 2010 17:29:49 -0700 (PDT), lu6etj
wrote:

what I do not know is how measure A and
B oscillator to distinguish each other... :D

I gave you that solution: multiply them. *Very simple exercise
available to anyone with sufficient bench equipment. *Skip the quotes
of undergraduate scribblers with little imagination that shrug their
shoulders at their own failure.

Humorous note: Richard Feynman do not share your dislike for
analogies he compare corks in water with charged objects fields :)

Feynman was a humorous fellow, but you are using undergrad texts
instead of his - why?

As I've already offered, drop all the frills and adornment and tell me
what scale the source of your 80M problem exists at:
1. *Subatomic,
2. *Atomic,
3. *Molecular.

73's
Richard Clark, KB7QHC

Hello Richard, good day.

Thank you very much for your friendly company, I enjoyed this
conversation but I think it is time to go back because it is leaning
dangerously close to an eristic exercise :)
I am sure we will have very interesting other things to talk about our
common topic.

Best regards

Your friend Miguel

what happens to reflected energy ?
 

On Jul 6, 12:17*am, Keith Dysart wrote:
On Jul 5, 6:19*am, K1TTT wrote:



On Jul 5, 1:26*am, Keith Dysart wrote:

On Jul 1, 8:53*am, K1TTT wrote:

On Jul 1, 12:37*pm, Cecil Moore wrote:

On Jun 30, 11:29*am, Keith Dysart wrote:

Check the a0 coefficient in the Fourier transform. This represents
the DC component of the signal.

And the result is zero EM waves, either forward or reflected, and your
argument falls apart.

Without this, how would you deal with a signal such as
* V(t) = 10 + 2 cos(3t)

If the cosine term is zero, there are zero EM waves, either forward or
reflected, and your argument falls apart.

Incidentally, V(t) = 10, is a perfect way to prove that energy and the
time derivitive of energy are not the same thing and your argument
falls apart.

Alternatively, one can use the standard trick for dealing with
non-repetitive waveforms: choose an arbitrary period. 24 hours
would probably be suitable for these examples and transform from
there. Still, you will have zero frequency component to deal
with, but there will be some at higher frequencies (if you
choose your function to make it so).

Windowing doesn't generate EM waves where none exist in reality and
your argument falls apart.
--
73, Cecil, w5dxp.com

a better argument is that a constant voltage produces a constant
electric field everywhere, since the field is not varying in time or
space there is no time or space derivative to create a magnetic field
so there can be no propagating em wave. *you could do the same with
zero or constant current producing a constant magnetic field.

The same question for you...

With an infinitely long transmission line excited by a step function,
is there an EM wave propagating down the line?

If not, what is it that is propagating down the line? Especially at
the leading edge?

essentially the dc case IS unique in that you must wait forever for it
to reach sinusoidal steady state since the lowest frequency component
is 0hz

You have used similar phrases before. Are you suggesting that an
open circuited transmission line excited with a step function takes
infinitely long to read steady state?

...Keith

'it depends'... in the special case you have concocted where the

'Concocted has such perjorative ring to it. Much better would be
'appropriately selected to illustrate a point'!

signal source has no reflections it only takes one round trip. *

Excellent. Some agreement.

this
case is very misleading if you try to extend it to cover other cases.
in general it takes infinitely long and you must account for the
infinite series of reflections. *

Of course. But this illustrates one of the benefits of "appropriately
selecting" examples. One can choose examples that do not take forever
to settle and therefore can be analyzed in finite time.

that is why the approximations

To which approximations do you refer?

used
to come up with the sinusoidal steady state solution is so useful, and
exactly why it can not be applied to steps and square waves and other
non sinusoidal constant sources.

Are you suggesting that it is inappropriate to use the reflection
coefficient computed at an impedance discontinuity to predict the
behaviour of a transmission line excited with a 'step, square wave or
other non sinusoidal constant sources"?

and in your infinite line example it never reaches steady state so the
step wave propagates forever

So is this 'step wave' an EM wave, according to your definition of an
EM wave? If not, what would you call it?

...Keith

correct, the 'step wave' is not AN EM wave, it is an infinite
summation of EM waves.