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In an A.C. L-C series circuit X_L > X_C. Hence the current ______.

Asked in GSEB Board July 2016 · Phase relationships and phasors

• (1) leads the voltage by π/2 in phase
• (2) lags behind the voltage by π/2 in phase
• (3) leads the voltage by π in phase
• (4) lags behind the voltage by π in phase

Step-by-step solution

Why the other options are wrong

• (1) This is the case X_C > X_L, when the net reactance is capacitive. With X_L > X_C the circuit behaves as an inductor, and the current in an inductor lags.
• (3) A phase difference of π would put the current in antiphase with the voltage, so the circuit would feed power back to the source on average. V_L and V_C are each π/2 from the current, so their sum is exactly π/2 from it.
• (4) Lagging by π is the same antiphase relation as leading by π, and just as impossible here: the net voltage I(X_L - X_C) is exactly π/2 ahead of the current.

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