To solve this problem we will apply the concepts related to volume, as a function of length and area, as of mass and density. Later we will take the same concept of resistance and resistivity, equal to the length per unit area. Once obtained from the known constants it will be possible to obtain the area by matching the two equations:
Mass of copper wire
Density
Resistively of copper
Resistance (R) = 0.390\Omega
Volume is defined as,
(1)
We know that,
(2)
Multiplying equation we have
Therefore the length of the wire is 1.68m