Question

In the given circuit the peak voltage across $C,L$ and $R$ are $30V$, $110V$ and $60V$ respectively. The rms value of the applied voltage is

• A. 100 V
• B. 200 V
• C. 70.7 V
• D. 141 V

Answer 1

Answer: (C)

$V_0=\sqrt{V_R^2+{\left(V_L-V_C\right)}^2}$
$=\sqrt{60^2+\left(110^2-30^2\right)}=100$
$V_{rms}=\frac{V_0}{\sqrt{2}}=\frac{100}{\sqrt{2}}$
$=\frac{100}{\sqrt{2}}\times \frac{\sqrt{2}}{\sqrt{2}}=100\times \frac{\sqrt{2}}{2}$
$=50\times 1.414=70.7V$