On Jan 1, 4:57*pm, Cecil Moore wrote:
Keith Dysart wrote:
Could you better describe how you determine that the source has a Z0
equal to the line Z0? *I can guess that you use a Thévenin equivalent
circuit and set the series resistor to Z0.

This will do it.

We have a black box. We use a 12vdc battery and a current
meter to measure the impedance of the black box. The
current meter reads zero when we connect the 12vdc battery
to the black box terminals. What is the impedance inside
the black box since test V/I = infinity?

Recall that impedance is the slope and to obtain
the slope you need to do two measurements. Only if
the entity is completely passive can you make only
one measurement because in that case the line passes
through the origin which is the implicit other
measurement.

With two measurements you will obtain the correct
impedance.

....Keith