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Old July 7th 10, 01:27 AM posted to rec.radio.amateur.antenna
Keith Dysart[_2_] Keith Dysart[_2_] is offline
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First recorded activity by RadioBanter: May 2007
Posts: 492
Default what happens to reflected energy ?

On Jul 6, 10:00*am, Cecil Moore wrote:
On Jul 6, 12:20*am, Keith Dysart wrote:

Is there a problem providing an answer?


I don't know how to measure the exact answer. How many photons does it
take to cause a measurable EM field at one cycle per two years?


Excellent attempt at diversion.

If the
EM field is too low to measure, how do you know it is there at all?


Plenty of joules are being moved per second. There is no reason to
expect the field to be small.

Blind faith in a math model?

Does either one of these views assist you with deciding whether
there are EM waves present during the one year intervals where
the signal value does not change?


No they don't. The problem is random/natural/man-made EM noise. When
the EM wave level drops far below the EM noise, how can you measure
the EM wave level? If you cannot measure it, you are back to angels on
the head of a pin.


The signal is well above the noise.

What if the signal was a sinusoid instead of square wave?

Is it then 'obviously' an EM wave?

If the square wave frequency was 1 MHz, would you have the same
difficulty deciding? Why not?


Because I could measure those EM waves.


Same joules per second. Lots of energy to detect. My 'diversion'
detector is still firing.

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.


No, EM waves do not exist at DC steady-state. Those are free electrons
which do not change orbital levels. The only force acting on an
electron during DC steady-state is a constant force.

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 have two phasor currents flowing into a junction. One current is
one amp at zero degrees. The other is one amp at 180 degrees. What is
the total current flowing out of the junction? Hint: There is no such
thing as a conservation of current principle. If the quantity can be
completely destroyed to zero at any time, it cannot be conserved.


I suppose that is an obtuse hint that you understand Kirchoff's
current law, but why not just come out and say it.

Assuming that you have grasped it, study how it is derived from
and relates to the 'conservation of charge' law. Remember that
current is the rate of flow of charge.

Then contrast those two laws with the previously discussed
power (rate of flow of energy) and 'conservation of energy'
law.

You should be able to discern the similarities.

....Keith