Power supply phenomenon:Can't go beyond a certain voltage even when knob turned

KeithRB:
You should have talked to an engineer, not a physicist.

While there might be some output resistance, in a decent supply - especially with voltage sensing - it can be very small. Like in the milliohm range. It usually has nothing to do with the amount of current a supply can deliver.

The Agilent 6626 can only output about .2 A, but the output impedance is about .03 ohms at DC.

Ok,dumb question(s): Isn't Impedance=Resistance in DC?
Why write output impedance when you could have written output resistance?
What's output resistance refer to here anyway?