OP AMP MCQ Level – 2 - Physics MCQ

The circuit connection of Op-Amp given in figure (i) and (ii) represents logarithmic amplifier for figure (i) and detector for figure (ii)
The correct answer is: Logarithmic amplifier for figure (i) and detector for figure (ii)

The frequency of oscillation f₀ is exactly the resonant frequency of balanced Wien bridge and is given by 

Assuming that the resistor are equal in value, and the capacitors are equal is value in the reactive lag of the wien bridge. At the frequency, the gain required for sustained oscillation is given by





The correct answer is:

V₀ = -2(1 + 2R/R) + (2 + sin 100 t)(1 + 2R/R)

= – 6 + 6 + 3 sin 100 t

= 3 sin 100 t

Applying the feedback will reduce the gain but increase the bandwidth hence, the gain bandwidth product = A_v x f. he remains constant for any voltage feedback amplifier.
The correct answer is: stays the same

At f = f_cc (cut o ff frequency at which gain falls to  of its low frequency value)


(i) Pass-Band gain = A_max = 1.5.
Hence,


The correct answer is: 

Let the inverting terminal of Op-Amp is at potential ‘V and hence non-inverting terminal also appears to have the same potential ‘V due to virtual ground concept.
Input current to op-amp is zero. Hence at non-inverting terminal mode, we have


Input current to Op-Amp is zero. Hence at inverting terminal mode we have

Substituting the values and solving all the above equations, we get

A and B can be measured at the same potential. From figure;


or

Also 


Combing (i) and (ii)

The correct answer is:

Similarly 


The correct answer is:

Similarly




The correct answer is: