Question

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

$R=5\Omega ,C=1mF,\omega =200rad{s}^{-1}$
As it is pure $RC$ circuit
$\therefore$ Current leads the voltage
by phase angle $\varphi$ given by
$tan\varphi =\frac{X_c}{R}=\frac{1}{\omega CR}$
$=\frac{1}{200\times 1\times 10^{-3}\times 5}=1$
$\therefore \varphi =ta{n}^{-1}\left(1\right)$
$=45^{\circ }$