In the circuit shown, supply voltage = ±15v, Va= +3v , Vb= -4v , Vc= +5v, R= R1= 1kΩ and RF= 2kΩ. 741 op-amp has A= 2×10^5 and R1= 10kΩ. Determine the output voltage internal resistance of the circuit?
(a) Vo ≅3v , RiF=6.67MΩ
(b) Vo ≅3v , RiF= 7MΩ
(c) Vo ≅3v , RiF=9.2MΩ
(d) Vo ≅3v , RiF= 3.5MΩ
I had been asked this question during an online interview.
The question is from Summing, Scaling & Averaging Amplifier topic in chapter Operational Amplifier Applications of Linear Integrated Circuits