Question

What is the impedance (as a function of frequency) of a 25nF capacitor in series with a 100 Ω resistor?

In series?

Answer 1

Ans. The capacitor and the resistor are in series, so the impedance Z = R + X_c

X_c = capacitive reactance and R = 100 Ohms

$X_c = \frac{1}{2\pi f C} \\ \\ \text{C = 25 nF } = 25*10^{-9} \ F\\ \\ \text{So, }X_c = \frac{1}{2\pi f*25*10^{-9}} =\frac{6.37*10^6}{f} \\ \\ \\ \text{The impedance Z} = 100 + \frac{6.37*10^6}{f} \ \Omega$