Answer: 850 W.
- A 850 W
- B 1000 W
- C 1175 W
- D 500 W
Correct answer: A. 850 W
Explanation: Apparent power S = 1 kVA = 1000 VA. Real power P = S × PF = 1000 × 0.85 = 850 W. The rest (reactive power) oscillates between source and load.
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.