Final answer:
If aluminum and copper wires have the same resistance, the wire with the larger diameter is copper. The resistance of a wire is inversely proportional to its cross-sectional area.
Step-by-step explanation:
If aluminum and copper wires have the same resistance, the wire with the larger diameter is copper.
The resistance of a wire is inversely proportional to its cross-sectional area. Since resistance is the same for both wires, the wire with the larger diameter will have a larger cross-sectional area, and therefore a smaller resistance.
For example, if the diameter of the aluminum wire is 2 mm and the diameter of the copper wire is 4 mm, the ratio of their resistances would be 1:4.