On Apr 14, 12:06*pm, Roger Sparks wrote:
On Mon, 14 Apr 2008 09:10:20 -0500

Cecil Moore wrote:
Keith Dysart wrote:
All the elements
of the system are completely specified in Fig 1-1 and we used
circuit theory to compute the energy flows. Not surprisingly, they
completely balanced:
* *Ps(t) = Prs(t) + Pg(t)

Yes, but that is only *NET* energy flow and says nothing
about component energy flow. Everything is already known
about net energy flow and there are no arguments about it
so you are wasting your time. Your equation above completely
ignores reflections which is the subject of the thread.

You object to me being satisfied with average energy flow
while you satisfy yourself with net energy flow. I don't see
one iota of conceptual difference between our two positions.

After hundreds of postings, all you have proved is that
Eugene Hecht was right when he said instantaneous powers
are "of limited utility", such that you cannot even tell
me how many joules there are in 100 watts of instantaneous
power when it is the quantity of those very joules that
are required to be conserved and not the 100 watts.

The limit in your quest for tracking instantaneous energy
is knowing the position and momentum of each individual
electron. Good luck on that one.

I am going to summarize the results of my Part 1 article
and be done with it.

In the special case presented in Part 1, there are only
two sources of power dissipation in the entire system,
the load resistor and the source resistor. None of the
reflected energy is dissipated in the load resistor
because the chosen special conditions prohibit reflections
from the source resistor. Therefore, all of the energy not
dissipated in the load resistor is dissipated in the source
resistor because there is no other source of dissipation
in the entire system. Only RL and Rs exist. Pr is not
dissipated in RL. Where is Pr dissipated? Even my ten year
old grandson can solve that problem and he's no future
rocket scientist.
--
73, Cecil *http://www.w5dxp.com

This thread has one assumption that I find very frustrating, a voltage source that is a steady source of power but can not absorb power. *My view is that any source must both absorb and deliver power at some none zero impedance. *

I am not sure why you desire a non-zero impedance. The usual
definition of an
ideal voltage source is that it provides or sinks what ever current is
needed to
hold the desired output voltage. When it is sourcing current then it
is providing
energy. No statement is made about where this energy comes from. When
it is
sinking current, it is absorbing energy. No statement is made about
where
this energy is going.

A non-zero impedance is not required to make any of the above
behaviour work.

If you include a non-zero impedance, then you have a more real world
source
which can often be modeled using the Thevenin equivalent circuit; an
ideal
voltage source (zero impedance) in series with a resistor representing
the impedance of the real world source.

As justification for this view, I offer that current always flows from high voltage to lower voltage, so a real voltage source would have to absorb energy if the external voltage exceeded the voltage of the voltage source.

This is true.

While it can be agrued that the ideal voltage source would have zero internal resistance, that argument does not address the fact that power flowing in the reverse direction (into the source, against the source supplied voltage) delivers *power into the source. *Charging a battery with zero internal resistance is a good example. *Another example is the observation that a generator becomes a motor when the externally suppied voltage exceeds the voltage supplied by the generator.

Yes, we can make the assumption that the voltage source can not absorb power at any time, but the assumption takes us into an unreal world and gives answers that are impossible to duplicate with measurements. *Some would call that a world of science fiction.

...Keith