Question

Determine Ad and Ac for the given circuit.

(a) Ac = 0 and Ad = 1

(b) Ac ≠ 0 and Ad = 1

(c) Ac = 0 and Ad ≠ 1

(d) Ac ≠ 0 and Ad ≠ 1

The question was posed to me in an interview for internship.

My question is from Difference Amplifiers in chapter Operational Amplifiers of Electronic Devices & Circuits

Answer 1

Right choice is (a) Ac = 0 and Ad = 1

For explanation I would say: Consider the fact that the potential at the input terminals are identical and obtain the values of V1 and V2. Thus obtain the value of Vd and Vc.