Answer: 1 (pure resistive at resonance).
- A 1 (pure resistive at resonance)
- B 0, as if the circuit carried no real power whatsoever
- C 0.707, the value corresponding to a 45 degree phase angle
- D 0.5, the value corresponding to a 60 degree phase angle
Correct answer: A. 1 (pure resistive at resonance)
Explanation: X<sub>L</sub> = X<sub>C</sub> = 10 Ω. Net reactance = X<sub>L</sub> - X<sub>C</sub> = 0. Z = √(R² + 0²) = R. Phase angle = 0. Power factor = cos(0) = 1.
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.