Question

A circuit containing a $20\Omega$ resistor and $0.1\mu F$capacitor in series is connected to 230 V ac supply of angular frequency 100 rad $s^{- 1}$The impedance of the circuit is

• A. $10^{5}\ \Omega$
• B. $10^{4}\ \Omega$
• C. $10^{6}\ \Omega$
• D. $10^{10}\ \Omega$

Answer 1

Answer: (A)

$10^{5}\ \Omega$

Answer 2

: Here, , $R = 20\Omega,C = 0.1\mu F$

$= 0.1 \times 10^{- 6}F$

$= 10^{- 7}F$

Impedance,$Z = \sqrt{R^{2} + \frac{1}{\omega^{2}C^{2}}}$

$= \sqrt{20^{2} + \frac{1}{(100)^{2} \times (10^{- 7})^{2}}}$

$= \sqrt{400 + 10^{10}}$ ≈ $10^{8}\Omega$