On Sun, 30 Dec 2007 12:28:29 -0800, Roger wrote:

When we define both the source voltage and the source impedance, we also
define the source power. Two of the three variables in the power
equation are defined, so power is defined.

Hi Roger,

I see a free mixing of "perfect" voltage and current sources, source
impedances, black boxes, and what appears (above) to be a forced
presumption of source power.

As is typical within these debates, something must be broken. For
one, these "perfect" sources paired with an impedance specification
necessarily describes a Thenvenin source (for some reason, no one sees
the elephant in their living room here). For every Thevenin source,
there is an equivalent Norton source; that, for either hidden within a
black box, is indistinguishable from the other.

Given this equivalency, the forced power presumption collapses. Power
in the black box (if in fact that is the intent of this coy
"perfection") cannot be known.

73's
Richard Clark, KB7QHC