# Electronic Devices - Op-Amp Applications - Discussion

### Discussion :: Op-Amp Applications - General Questions (Q.No.8)

8.

Determine the output voltage when V1 = V2 = 1 V.

 [A]. 0 V [B]. –2 V [C]. 1 V [D]. 2 V

Answer: Option A

Explanation:

No answer description available for this question.

 Divya said: (Dec 12, 2011) The given ckt is a differential amplifier ckt. Vo=(Rf/R1)*(V2-V1) Vo=(100/100)*(1-1)=0

 Mallik said: (Mar 26, 2012) Assume common voltage at two terminals to be vb; lets write KCL for the ckt [(v1-vb)/100k]+[(V0-Vb)/100k]= 0; [(V2-Vb)/20k] = Vb/20k; => V0 = V2-V1; =0

 Sunil said: (Jan 4, 2015) What we are talking about is op-amp? Which amplifies the difference between two signals? Here, difference between two signal is 0(v1-v2). And also, the CMRR Common Mode Rejection Ratio.

 Gurpreet said: (Jul 15, 2015) @Sunil brother in actual practice v1 and v2 are not equal but nearly equal.

 Ezhil said: (Jan 16, 2017) Consider the nodes after two input resistance as v3. Bby using node analysis method. (v3-v1)/100k + (v3-vo)/100k =0-----(1). (v3-v2)/20k + (v3/)20k =0--------(2). Sub v1=v2=1 in above equatios. We get v3= 1/2 sub this in equ 1. ve get vo =0.

 Rajan said: (Apr 29, 2020) I think the answer is 1v (by virtual short method). Because both the input resistor and feedback resistor are unequal hence we cant apply standard differential op-amp formula Vo= Rf/Rin(V2-V1).

 Abhi K said: (Aug 14, 2022) I think the answer should be, If we apply both inverting and non-inverting formulas. Then multiply by (V1-V2). (-Rf/R1) + 1 + (Rf/R2) * (V1-V2). (-100/100)+ 1 + (100/20) * (1-1). = 0.

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