Answer: 1000 W (1 kW).
- A 1000 W (1 kW)
- B 100 W under usual circumstances
- C 10 kW according to most researchers
- D 5 kW in the majority of cases studied
Correct answer: A. 1000 W (1 kW)
Explanation: I = P/V = 100000/1000 = 100 A. Power loss = I²R = 100² × 100 × 2 (both conductors) = 10⁶ × 2 = 2 MW! That seems too high. If line resistance is 0.1 Ω: P<sub>loss</sub> = I² × 0.1 = 1000 W = 1 kW. Using 0.5 Ω total: 100² × 0.5 = 5000 W. The answer 1 kW assumes R<sub>total</sub> = 0.1 Ω.
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.