Power Measurement Basics

[MarkE]

You've re-stated basically what the diagram is depicting, but how did you come to the conclusion that the battery dissipates -10W, or the resistor +10W?

Why did you not conclude that the battery was dissipating +10W and the resisitor -10W?

There are two possible conventions.  Either works mathematically provided one applies it consistently.  I chose the convention used throughout industry and academia. 

[poynt99]

There are two possible conventions.  Either works mathematically provided one applies it consistently.  I chose the convention used throughout industry and academia.

Would you mind showing your calculations?

[poynt99]

They do not oppose.  Both probes are in phase.  In order to oppose one must be CCW and the other CW from the reference node.

Please show diagrammatically what you mean.

[poynt99]

Which is the reason that I object to your choice of positive power as that supplied by a source when the common convention for positive power is the quantity dissipated by loads.

Mark, please quote me where I stated that a measured source power computes to a positive value.

If one is intent on educating folks, which is a good thing, teaching them to go against accepted conventions is a recipe for confusion and dissent.

Agreed, which is why I'm continuing with this discussion.

[MarkE]

Would you mind showing your calculations?

Take the test case I offered driving a 1 Ohm load with a series 1 mOhm CSR.  Use the diagram of that I posted.  We are assuming lossless wiring and no hidden circuit elements:

Label the nodes:  Source negative terminal / CSR bottom Node 0
CSR / load Node 1
Source positive terminal / load top Node 2

Vload = V2 - V1
Vcsr = V1
Iloop = V2/(Rload + Rcsr)
Pload = (V2^2 - V2*V1) / (Rload + Rcsr)

Since Rcsr << Rload, then Rload ~= Rload + Rcsr and V2 ~= V2 - V1, then Pload ~= V2*V1/Rcsr