rickman wrote:

On 7/20/2015 9:46 AM, Roger Hayter wrote:
John S wrote:

On 7/20/2015 4:06 AM, Roger Hayter wrote:
John S wrote:

On 7/19/2015 9:16 AM, John S wrote:
On 7/10/2015 7:38 PM, John S wrote:

On 7/10/2015 9:30 AM, Roger Hayter wrote:
I may not have defined the generator adequately. I meant that the
generator will supply one watt regardless of the impedance it sees.


That is your fallacy. A generator (not even a theoretical ideal one)
will not supply one watt regardless of the impedance it sees.

In what way is it a fallacy? There are theoretically only two possible
conditions where it is impossible. Do you know what those two conditions
are?

I should not be asking that question. I should be supplying some
information. I apologize.

The two conditions are a zero ohm load and an open circuit (infinite
load). It is not theoretically possible to put power into either. Those
two conditions require a source such that the results are,
mathematically, undefined.

But ALL other conditions are theoretically possible.

I don't think a true open circuit is actually possible, though one can
make a pretty good approximation.



Correct. And neither is a true short circuit. But, I was sticking to
theoretical conditions rather than getting into how much of a short or
open circuit really is.

Would a superconductor not be a true short circuit? Anyway, I thought
you were specifically talking about what was "possible" rather than
theoretical limits. Your all-purpose 1 W amplifier could have an output
voltage or current than approached infinity as the output load
approached open circuit and short circuit, if you are still talking
theoretically.

Even if a conductor has no dissipative resistance, won't all conductors
have radiation resistance? It is normally so small that it can be
ignored, but in the case of a true zero ohm conductor it would be more
significant.

Good point. And does a superconducting electromagnet show a real
resistance when the field does mechanical work? Naive thermodynamics
would seem to suggest it should, but the maths is well beyond me.


--
Roger Hayter