The figure gives the electric potential V(x) along a copper wire carrying uniform current, from a point of higher potential Vs = 9.00 μV at x = 0 to a point of zero potential at xs = 3.20 m. The wire has a radius of 1.50 mm, and copper has a resistivity of 1.69 × 10-8 Ω·m. What is the current in the wire?
p = 1.69*10^-8 (ohm * meter) for copper
The Attempt at a Solution
I solved it by just plugging values into the above equation give. It is clear that A>0 (cross section), L > 0 (length), p > 0 (given constant). And V < 0 because Vf = 9*10^-6 and Vi = 0.
The answer is +1.176e-3, but I got a negative value. As you can see, every value is positive except delta V, because Vf < Vi, so the current should be negative, should it not?