Which two factors determine a conductor's resistance?

• A. Size and length
• B. Color and density
• C. Material and grade
• D. Voltage and current

Answer: (A)

Resistance in a conductor is set by how long it is and how thick it is. The longer the wire, the more resistance electrons encounter as they travel, so R rises with length. A larger cross-sectional area provides more pathways for current, which lowers resistance, so R falls as the size increases. For a given material (fixed resistivity), resistance follows R = ρL/A, meaning length and cross-sectional area are the direct geometric factors that determine it. The color or density don’t determine resistance in this model, and while the material’s resistivity (a property of the material) matters, the two factors you adjust to change resistance are length and size. Voltage and current are related to resistance through Ohm’s law, but they do not set the resistance itself.