A Thevenin equivalent can also be determined from measurements made at the pair of terminals of interest. Assume the following measurements were made at the two external terminals a, b of a circuit.
When a 20-ohm resistor is connected between terminals a and b, the voltage vab is measured and found to be 100 V.
When a 50-ohm resistor is connected between terminals a and b, the voltage vab is measured and found to be 200 V.
Find the Thevenin equivalent of the network with respect to terminals a, b.