Question

In $R-C$ circuit $\omega=100\, rad \,s ^{-1},\, R =100\, \Omega,\, C =20\, \mu\, F$. What is impedance?

• A. $510\,\Omega$
• B. $200\, \Omega$
• C. $250\, \Omega$
• D. $300\, \Omega$

Answer 1

Answer: (A)

Impedance for an R-C circuit is given by
$Z =\sqrt{R^{2}+X_{C}^{2}}=\sqrt{R^{2}+\left(\frac{1}{\omega C}\right)^{2}}$
$ =\sqrt{(100)^{2}+\left(\frac{1}{100 \times 20 \times 10^{-6}}\right)^{2}}$
$=\sqrt{10^{4}+25 \times 10^{4}}$
$=100 \sqrt{26}$
$=510\, \Omega$