Question

At the same temperature, two wires made of pure copper have different resistances. The same voltage is applied at the ends of each wire. The wires may differ in?

1) Length
2) Thickness
3) Material
4) Temperature

Answer 1

The resistance of two copper wires at the same temperature can differ due to variations in length or thickness, but not due to material or temperature as these are constant.

Step-by-step explanation:

When dealing with two pure copper wires at the same temperature and with the same voltage applied, the differences in resistance can be attributed to variations in their physical dimensions. Differences in resistance can arise if the wires differ in length or thickness (cross-sectional area). The material and temperature are ruled out since the wires are of the same material (pure copper) and are at the same temperature.

Addressing one of the given examples, if a wire is drawn through a die and stretched to four times its original length, its resistance increases by the square of the stretching factor if its cross-sectional area remains uniform. Since the wire is stretched to four times its length, resistance increases by a factor of 42, which is 16. This is due to the direct proportionality of resistance to the length of the wire, given by the formula R = ρL/A, where R is resistance, ρ is resistivity, L is the length, and A is the cross-sectional area.