Q. In a series L-C-R circuit $R = 200\ \Omega$ and the voltage and the frequency of the main supply is 220V and 50 Hz respectively. On taking out the capacitance from the circuit the current lags behind the voltage by $30{^\circ}$. On taking out the inductor from the circuit the current leads the voltage by $30{^\circ}$. The power dissipated in the L-C-R circuit is
A) 305 W
B) 210 W
C) Zero
D) 242 W
Explanation
(d) The given circuit is under resonance as $X_{L} = X/C$
Hence, power dissipated in the circuit is
$P = \frac{V^{2}}{R} = 242\ W$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.