Question

An $AC$ voltage source $V=200\sqrt{2}\sin 100t$ is connected across a circuit containing an $AC$ ammeter (it reads $rms$ value) and capacitor of capacity $1\mu F$. The reading of ammeter is:

• A. $10mA$
• B. $20mA$
• C. $40mA$
• D. $80mA$

Answer 1

The correct option is B $20mA$

Given $E=200\sqrt{2}\sin 100t$

Hence,

$\omega =100rad/sec$

and

$E_{rms}=\frac{200\sqrt{2}}{\sqrt{2}}=200$

$C=1\times {10}^{-6}F$

$X_C=\frac{1}{\omega C}=\frac{1}{100\times 1\times {10}^{-6}}={10}^4\Omega$

$I=\frac{E_{rms}}{X_C}$

$I=\frac{200}{{10}^4}$

$I=2\times {10}^{-2}A$

$I=20mA$