. Determine the relation between the current and drift veloctiy
Consider conductor of cross-sectional area A in which electric field E exists. The drift velocity of electrons is υd . Take a length vd Δt of conductor. The volume of this portion is Avd Δt . (See figure) If n is the number density of electrons in the conductor, i.e.,the number of electrons per unit volume, the total magnitude of charge contained in the cylinder of volume Avd Δt is neAvd Δt .