Question

A resistance of $ 5 \Omega $ is connected in series with a capacitance of $ 1\,mF $ . The combination is connected to $ AC $ source of angular frequency $ 200 \, rad\, s ^{-1} $ . Then

• A. the voltage leads the current by $ 45^{\circ} $
• B. the current leads the voltage by $ 45^{\circ} $
• C. the current leads the voltage by $ 60^{\circ} $
• D. the voltage leads the current by $ 60^{\circ} $

Answer 1

Answer: (B)

$R=5 \Omega, C=1mF, \omega=200\,rad\,s^{-1}$
As it is pure $RC$ circuit
$\therefore $ Current leads the voltage
by phase angle $\phi$ given by
$tan \,\phi=\frac{X_{c}}{R}=\frac{1}{\omega CR}$
$=\frac{1}{200\times1\times10^{-3}\times5}=1$
$\therefore \phi=tan^{-1} \left(1\right)$
$=45^{\circ}$