Expression for drift velocity

Consider a section of a metallic conductor of length l and cross-section area A. Let n be the no. of electrons per unit volume of the conductor. Then,

volume of the conductor = Al

no .of electrons in this volume = nAl

Total charge (Q) = nAel; where e is and electric charge.

On connecting a battery of potential V, Q charge flows through the conductor in time t. then current is