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⚛️ Physics  ·  Alternating Current  ·  NEET & JEE

Q-factor of a series LCR circuit:

Answer: omega_0 L/R.

  • A omega_0 L/R
  • B R/(omega_0 L)
  • C omega_0/(LC)
  • D L/(omega_0 RC)

Correct answer: A. omega_0 L/R

Explanation: Q = omega_0 L/R = 1/(omega_0 CR). High Q means sharp resonance, less energy loss per cycle.

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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