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## Homework Statement

The figure gives the electric potential

*V(x)*along a copper wire carrying uniform current, from a point of higher potential

*V*s = 9.00 μV at

*x*= 0 to a point of zero potential at

*x*s = 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?

http://edugen.wileyplus.com/edugen/courses/crs7165/art/qb/qu/c26/q24.jpg

## Homework Equations

p(I/A)=V/L

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?