Question

If a capacitor of $8\mu F$ is connected to a $220V$, $100Hz$ ac source and the current passing through it is $65mA$, then the rms voltage across it is

• A. $129.4V$
• B. $12.94V$
• C. $1.294V$
• D. $15V$

Answer 1

Answer: (B)

Here, $V_{rms}=220V$,
$I_{rms}=65mA=0.065A$
$C=8\mu F=8\times 10^{-6}F$,
$\upsilon =100Hz$
Capacitive reactance,
$X_C=\frac{1}{2\pi \upsilon C}$
$=\frac{1}{2\times 3.14\times 100\times 8\times 10^{-6}}$
$=199\Omega$
Then rms voltage across the capacitor is
$V_{Crms}=I_{rms}{X}_C=0.065\times 199$
$=12.94V$