Ohm's Law in Vector Form

Write vector form of Ohm' law universal? Show graphically ohmic and-ohmic nature of the conductors, giving examples of each.

Ohm’s law may also be stated by the equation $\stackrel{\rightharpoonup }{\mathrm{j}}=\mathrm{\sigma } \stackrel{\rightharpoonup }{\mathrm{E}}$. What do the symbols$\stackrel{\rightharpoonup }{\mathrm{j}}$, $\sigma$ and $\stackrel{\rightharpoonup }{\mathrm{E}}$  stand for? Show that the combination of units on the two sides are identical.