Electronic Devices - Op-Amp Applications - Discussion

Discussion :: Op-Amp Applications - General Questions (Q.No.2)


Calculate the output voltage if V1 = –0.2 V and V2 = 0 V.

[A]. 0 V
[B]. –6.6 V
[C]. –4 V
[D]. 2 V

Answer: Option D


No answer description available for this question.

Amit Bhattacharya said: (Oct 6, 2011)  
As v2 is zero so that branch can be neglected
i.e. 10k can be neglected

Now the circuit is simple non inverting amp
and v0=(-Rf/R1)*v1

Vandana said: (Jan 4, 2012)  
It is not a non inverting amplifier, it is an simple inverting amplifier. If it is a non inverting amplifier then formula for voltage output should be diffrent.

Mallik said: (Mar 26, 2012)  
As the figure shows.. op-amp used here is inverting amplifier. From the circuit configuration we can conclude that it is an adder , where inputs are given to inverting port. the formula goes in the following way..

Vout = -[{(V1/R1)+(V2/R2)}/{(1/Rf)}]

Here V1= -0.2v; V2= 0v R1= 33k; R2=10k ; Rf=330k
=> Vout = -[(V1/R1)*Rf]
Vout= -[V1*(330k/33k)]
Vout = -[-0.2*10]
Vout = 2v

Dipanjan said: (May 10, 2012)  
Ii=(V1-0)/33 [Ii=input current through 33k)
If=(V0-0)/330 [If=feed back current through 330k)
I-=(Ii)+(If) [Kirchhoff law at opamp input node]
As input impedance of opamp is Infinite So Input current(I-) is zero.

Mma said: (Dec 4, 2013)  
Vout = -330k{(-0.2/33k)+(0/10k)}.

= -330k(-0.2/33k).

= 2 volt.

Indu said: (May 11, 2015)  
Here given the amplifier is summing opamp and the solution of the given problem.

vo = -[330/33 (-0.2)] = 2 v.

Mb3R said: (Nov 15, 2015)  
What the different between non and inverting op amps?

Seema Rajput said: (May 23, 2016)  
Vo = (-Rf/R1)V1 + (-Rf/R2)V2.
= (-330k/33k) * (- 0.2v) + (- 330/10k) * 0.
= (- 10) * (-0.2) + 0.
Vo = 2V.

Surya said: (Feb 28, 2017)  
If the voltage source is connected to the positive terminal of an op amp and ground is connected to the negative terminal of the op amp then it's called as "non-inverting amplifier". If the terminals are reversed then acts as inverting amplifier.

Raviraj said: (Mar 2, 2017)  
vo = -[330/33 (-0.2)] = 2v.

Neeharika said: (May 12, 2017)  
By nodal analysis (0 -V1)/33k+(0-V0)/330k = 0.
0.2/33k-V0/330k = 0.
V0 = 2v.

Muhammad Younas said: (May 19, 2017)  
Good work, Thanks for explaining it.

Amit said: (Feb 22, 2018)  
As we see in the circuit, -o.2 is applied at the negative terminal so the op-amp is inverting op-amp. By general description, we calculate drop across 33k by ohms law. We get 1/165 amp and in other branches we applied same ohms law and we get 0 amp coz v=0v. Now add both the currents and applied again ohms law at feedback branch 330k we get vo= 2volt.

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