Answer: X C > X L (f 0 ).
- A X<sub>C</sub> > X<sub>L</sub> (f < f<sub>0</sub>)
- B X<sub>L</sub> > X<sub>C</sub> (f > f<sub>0</sub>)
- C X<sub>L</sub> = X<sub>C</sub>
- D R > X<sub>L</sub>
Correct answer: A. X<sub>C</sub> > X<sub>L</sub> (f < f<sub>0</sub>)
Explanation: When X<sub>C</sub> > X<sub>L</sub>, the circuit is predominantly capacitive. Current leads voltage. This occurs when operating frequency is below the resonant frequency f<sub>0</sub> = 1/(2π√(LC)).
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.