Introduction to Electrical Engineering

A: The correct choice ensures a low-impedance, deterministic fault return path so touch voltage collapses before injury risk. Using mounting screws assumes contact integrity that vibration and paint destroy. Higher insulation class doesn’t address exposed metal under a fault. An RCD trips on imbalance, not on ensuring fault current magnitude.

A: This option handles fast edges and isolation without saturating or aliasing. A CT distorts under low-frequency components and can saturate with DC bias. A shunt injects loss and EMI into the link and ignores peaks. A bare Rogowski coil gives derivative output and misleads control without conditioning.

A: The right answer explains voltage rise through impedance and reactive current reduction. Capacitors don’t create real power. Tap changers respond slowly and aren’t triggered by a single bank. Resonance affects distortion more than steady fundamental magnitude here.

A: This lands in the few-volt range using known copper resistivity and length. Perfect-conductor thinking ignores real resistance. Skin effect is negligible at mains frequency and this cross-section. Doubling length is already implicit and doesn’t explode the drop.