Let's see. Current (I) = charge / time it takes to travel. I=q/t Length of the conductor = L = V*T (as velocity=L/T) Say n=number of electrons/volume=10^29 electrons/m^3 e=charge of the electron A=area of the bar (0.6 * 9 cm) Then q=neAL= neAV*T Then I=q/t= neAV Then V=I/neA. Plug in the values. Do some readings if you want to be an Engineer. Double check my equation, I wrote it in a haste.