Which of the following does not affect wire resistance?

• A. Material
• B. Length
• C. Type of power
• D. Temperature

Answer: (C)

Resistance in a wire is determined by its material, its cross-sectional area, and its temperature; the way you drive the current doesn’t change the resistance itself. The intrinsic value of resistance comes from R = ρL/A, where ρ is the resistivity of the material (which varies with the type of material and with temperature), L is the length, and A is the cross-sectional area. Longer wires or smaller cross-sections increase resistance, and as temperature rises, most metals experience higher resistivity, which raises resistance. The type of power—whether the current is direct or alternating—does not alter the resistance, though it can affect how the circuit behaves overall (for example, in AC circuits you also consider impedance and reactance). The important takeaway is that the intrinsic resistance depends on material, size, and temperature, not on whether the current is DC or AC.