Question

Given that the maximum gain of a low pass filter using op-amp is 5.5 and the resistor R1 = 10kΩ, find the value of R2.

(a) 220kΩ

(b) 55kΩ

(c) 50Ω

(d) -55kΩ

I have been asked this question by my college professor while I was bunking the class.

I would like to ask this question from Frequency Filters topic in division Op-amps and its Applications of Analog Circuits

Answer 1

Correct answer is (b) 55kΩ

For explanation I would say: The maximum gain is at low frequencies and at low frequencies, the capacitance reactance is infinite and thus the total feedback impedance ZF = RF = R2

Thus gain = -ZF/Z = -R2/R1

Amplitude = 5.5 = R2/R1 = R2/10k

R2 = 55kΩ.