Question

The value of α in the attenuation band of constant k-low pass filter is?

(a) α=2 cosh^-1⁡(fc/f)

(b) α=cosh^-1⁡(f/fc)

(c) α=2 cosh^-1⁡(f/fc)

(d) α=cosh^-1⁡(fc/f)

This question was addressed to me in final exam.

This interesting question is from Constant-K Low Pass Filter in division Filters and Attenuators of Network Theory

Answer 1

Right choice is (c) α=2 cosh^-1⁡(f/fc)

Easy explanation: α = 2 cosh^-1[Z1/4Z2] and Z1/4Z2 =  f/fc. On substituting we get α = 2 cosh^-1⁡(f/fc).