An inductor \( 20\text{ mH} \), a capacitor \( 50\text{ }\mu\text{F} \) and a resistor \( 40\text{ }\Omega \) are connected in series across a source of emf \( V = 10\sin 340t \). The power loss in A.C. circuit is

Here \( \omega = 340\text{ rad/s} \). \( X_L = \omega L = 340 \times 20 \times 10^{-3} = 6.8\text{ }\Omega \). \( X_C = \frac{1}{\omega C} = \frac{1}{340 \times 50 \times 10^{-6}} \approx 58.8\text{ }\Omega \). Impedance \( Z = \sqrt{R^2 + (X_C - X_L)^2} \approx \sqrt{40^2 + (52)^2} \approx 65.6\text{ }\Omega \). Power \( P = \frac{V_{rms}^2 R}{Z^2} \approx 0.51\text{ W} \).