Cecil Moore wrote:
Roger Sparks wrote:
You write "The only other device in the entire system capable
of dissipation is the source resistor." which is a correct statement.

Therefore, all power dissipated in the circuit must be dissipated
in the load resistor and the source resistor because there is
nowhere else for it to go. Since the reflected power is not
dissipated in the load, by definition, it has to be dissipated
in the source resistor but not at the exact time of its arrival.
There is nothing wrong with delaying power dissipation for 90
degrees of the cycle. In Parts 2 and 3 of my articles, I will show
how the source decreases it power output to compensate for destructive
interference and increases it power output to compensate for
constructive interference.

Unfortunately, the circuit is intended to illustrate the absence of

[AVERAGE] interference under special circumstances but an instant
analysis shows

that all the power can not be accounted for.

Not surprising since there is no conservation of power principle.

The concept of a wave is energy located at a predicted place after some
time period. That is a concept of conservation of power.

We can only conclude that

[instantaneous] interference is present. Not good because the circuit
was intended to

illustrate a case of NO [AVERAGE] interference.

I took the liberty of adding adjectives in brackets[*] to your
above statements. It doesn't matter about the instantaneous values
of power since not only do they not have to be conserved, but they
are also "of limited usefulness", according to Eugene Hecht, since
the actual energy content of instantaneous power is undefined even
when the instantaneous power is defined.

The circuit is very useful to investigate interference more carefully
because on the AVERAGE,

the interference IS zero. Using spreadsheets, we can see how the
interference both adds and

subtracts from the instantaneous applied voltage, resulting in cycling
variations in the power

applied to the resistor and other circuit elements. A very instructive
exercise.

Instructive as long as we remember that a conservation of power
principle doesn't exist and therefore, equations based on instantaneous
powers do not have to balance. The joules, not the watts, are what must
balance.

Forget the conservation of power at your own peril, because we need to
depend upon the predictability of waves of energy acting over time to
solve these problems. When the instantaneous powers do not balance, we
know that we do not yet have the complete solution or complete circuit.


73, Roger, W7WKB