Which four factors affect the resistance of wires?

• A. length, cross sectional area, temperature, insulation material
• B. length, insulation color, temperature, environment
• C. length, cross sectional area, temperature, type of conductor
• D. length, cross sectional area, insulation thickness, heat

Answer: (C)

Resistance in a wire comes from its geometry, the material, and the temperature. The mathematical heart is R = ρL/A, which shows that longer wires raise resistance and larger cross-sectional area lowers it. Temperature matters because, for metals, resistivity rises with temperature, so the same wire will have higher resistance when hotter. The material itself sets the resistivity: different conductors (copper, aluminum, nichrome, etc.) have different inherent resistances per length. Insulation, color, or environment don’t directly set the wire’s resistance (they can influence temperature, but they aren’t intrinsic factors). So the four factors that determine resistance are length, cross-sectional area, temperature, and the type of conductor.