Answer: Equals R (minimum).
- A Is maximum during normal conditions
- B Equals R (minimum)
- C Equals L/C as generally observed
- D Is zero in typical laboratory settings
Correct answer: B. Equals R (minimum)
Explanation: At resonance: XL = XC, so they cancel. Z = sqrt(R<sup>2</sup> + (XL-XC)<sup>2</sup>) = sqrt(R<sup>2</sup>) = R. Minimum impedance = R.
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.