Question

If the supply voltage $V_s$ is 5 V then the Thevenin equivalent resistance seen at terminals A-B for the Op-amp circuit is ________ k$\Omega$

• A. 16

Answer 1

The correct option is A 16
Finding $R_{Th}$

Consider figure in which $V_s=0$ and there is an external 1 A excitation with $V_s=0,$ the Op-amp gain implies $V_{CB}=0,$ despite the presence of the 1 A current source from KVL

$V_{AB}=16k\Omega \times 1+V_{CB}=16kV$

Hence $R_{Th}=\frac{V_{AB}}{1}=\frac{16}{1}=16k\Omega$