Answer: It becomes one-ninth.
- A It becomes one-third
- B It becomes three times
- C It becomes one-ninth
- D It remains unchanged
Correct answer: C. It becomes one-ninth
Explanation: For fixed transmitted power, P = VI, so increasing voltage by a factor of 3 reduces current by a factor of 3. Line loss is I<sup>2</sup>R, so the loss becomes 1/9 of its original value.
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.