WAEC Physics 2024 Paper

Concept:Power loss during transmission depends on current, so reducing current lowers loss.Explanation:Long-distance transmission uses high voltage to lower the current.Line loss is given by $P_{\text{loss}} = I^2R$, where $I$ is current and $R$ is line resistance.Lower current means much smaller $\mathrm{I}^2R$ loss, making transmission more economical.Alternating current (AC) is preferred because it can be easily stepped up or down using transformers.Therefore, AC at high voltage and low current is the most economical method.Answer:A. Alternating current at high voltage and low current.