A lowpass filter consists of a 114μF capacitor in series with a 155Ω resistor. The circuit is driven by an AC
Part A
What is the crossover frequency fc?
fc =
Part B
What is Vc when f=1/2 fc?
Part C
What is Vc when f=fc?
1 Answer

A) fc = 1/(2*pi*R*C) = 9 Hertz
C) when f= fc, Vc = 0.707(V in)
This is because Xc = R
Vc = (V in)(jXc/(R + jXc) = (V in)(j/(1+j)
Vc = V in(1/(sqrt 2) = 0.707 Vin
B) when f = 1/2(fc), Vc = 0.89(V in)
Xc = 2R
Vc = (V in)(j2/(1 +j2)
Vc = V in(2/(sqrt 5) = 0.89(V in)