Question

In the circuit shown in the figure, the $AC$ source gives a voltage $V=20\cos \left(2000t\right)$. Neglecting source resistance, the voltmeter and ammeter reading will be:

• A. $0V,0.47A$
• B. $1.68V,0.47A$
• C. $0V,1.4A$
• D. $5.6V,1.4A$

Answer 1

The correct option is D $5.6V,1.4A$

We know

$Z=\sqrt{(R{)}^2+(X_L-X_C{)}^2}$

Here $R=10\Omega ,X_L=\omega L=2000\times 5\times {10}^{-3}=10\Omega$

$X_C=\frac{1}{\omega C}=\frac{1}{2000\times 50\times {10}^{-6}}=10\Omega$

So,

$Z=\sqrt{(10{)}^2}$

$Z=10\Omega$

Maximum current $i_{)}=\frac{V_0}{Z}=\frac{20}{10}=2A$

Hence,

$I_{rms}=\frac{2}{\sqrt{2}}=1.4A$

$V_{rms}=4\times 1.4=5.6V$