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⚛️ Physics  ·  Alternating Current  ·  NEET & JEE

For a series RLC circuit, the condition for the current to lead the voltage (capacitive behavior) is:

Answer: XC > XL (f < f0).

  • A XC > XL (f < f0)
  • B XL > XC (f > f0)
  • C XL = XC
  • D R > XL

Correct answer: A. XC > XL (f < f0)

Explanation: When XC > XL, the circuit is predominantly capacitive. Current leads voltage. This occurs when operating frequency is below the resonant frequency f0 = 1/(2π√(LC)).

V and I Phase Relationships in AC CircuitsPure Inductor: I lags V by 90°VIPure Capacitor: I leads V by 90°VIMemory aid "ELI the ICE man": in an inductor (L) E(V) leads I; in a capacitor (C) I leads E(V)For a pure resistor, V and I stay perfectly in phase (no lag or lead at all)

In a pure inductor the current lags the voltage by 90° (energy is briefly stored in the magnetic field before current responds); in a pure capacitor the current leads the voltage by 90° (current must flow to build up charge before voltage rises) - the mnemonic "ELI the ICE man" keeps these straight.

Concept context

AC circuits, impedance, LCR series circuit, resonance, transformers, and power factor.

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