For an inverting amplifier with input resistor R1 and feedback resistor Rf, the closed-loop voltage gain is which?
AA_v = +Rf/R1
BA_v = -Rf/R1
CA_v = R1 + Rf always
DA_v = R1/Rf with minus sign
Answer & Solution
Correct answer: B. A_v = -Rf/R1
Inverting config: virtual ground at V-, so I1 = Vin/R1 = -Vout/Rf ⟹ Vout/Vin = -Rf/R1. Independent of op-amp open-loop gain.
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