A 280-km-long high-voltage transmission line 2.0 cm in diameter carries a steady current of 1,110 A. If the conductor is copper with a free charge density of 8.5 x 1028 electrons per cubic meter, how many years does it take one electron to travel the full length of the cable? (Use 3.156 x 107 for the number of seconds in a year.) Express the average time of travel for the charge in terms of distance and average speed. Then express the average speed in terms of the density of carriers, the charge of each carrier, and the electric current produced by the flow of charge. yr Need Help? Read It Master It