An LCR circuit contains resistance of 110 Ω and a supply of 220 V at 300 rad/s angular frequency. If only capacitance is removed from the circuit, current lags behind the voltage by 45 °. If on the other hand, only inductor is removed the current leads by 45 ° with the applied voltage. The rms current flowing in the circuit will be: (a) 1 A (b) 2.5 A (c) 2 A (d) 1.5 A

Answer: (c). Without C, lag 45°: XL = R. Without L, lead 45°: XC = R. So XL = XC: resonance, Z = R = 110 Ω. I = 220/110 = 2 A, so the answer is (c).

An LCR circuit contains resistance of 110 Ω and a supply of 220 V at… | JEE Main 2021 (25 Feb, Shift 2)

Q60JEE Main 2021 · 25 FEB · SHIFT 2Difficult

Power, Power Factor & Wattless Current

An LCR circuit contains resistance of 110 $\Omega$ and a supply of 220 V at 300 rad/s angular frequency. If only capacitance is removed from the circuit, current lags behind the voltage by 45 $^\circ$ . If on the other hand, only inductor is removed the current leads by 45 $^\circ$ with the applied voltage. The rms current flowing in the circuit will be:

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Answer: (c)

Without C, lag $45^\circ$ : $X_L = R$ . Without L, lead $45^\circ$ : $X_C = R$ .
So $X_L = X_C$ : resonance, $Z = R = 110\ \Omega$ .
$I = 220/110 = 2$ A, so the answer is (c).

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