Question

An alternating voltage $E=200\sqrt{2}sin\left(100t\right)$ is connected to a $1\mu F$ capacitor through an A.C. ammeter. The reading of the ammeter shall be :

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

Answer 1

The correct option is B $20mA$

Root mean square voltage across the capacitor=$\frac{V_m}{\sqrt{2}}$

$=\frac{200\sqrt{2}}{\sqrt{2}}=200V$

Reactance of the capacitor = $\frac{1}{\omega C}$

$=\frac{1}{100\times {10}^{-6}}=10000\Omega$

Thus reading of ammeter=$\frac{V_{rms}}{X_C}=\frac{200}{10000}A=20mA$