When is an electric current produced? Explain.

(N/A) An electric current is produced when there is a net flow of electric charge through a cross-section of a conductor over a period of time.
$1$. In a conductor,free electrons are in random motion due to thermal energy,resulting in no net flow of charge.
$2$. When an external electric field $(E)$ is applied across the conductor,the free electrons experience an electric force $(F = -eE)$,causing them to drift in the direction opposite to the applied field.
$3$. This directed motion of charge carriers constitutes an electric current $(I)$.
$4$. Mathematically,current is defined as the rate of flow of charge: $I = \frac{dq}{dt}$,where $dq$ is the net charge passing through a cross-section in time $dt$.