Question

mention the condition under which a current flow in a conductor

Answer 1

The condition under which charges can move in a conductor are the charges in which there is a potential difference.

A 12-volt battery would supply 12 Joules of electric potential vitality per each 1 Coulomb of charge which moves between its negative and positive terminals. The proportion of the adjustment in potential energy to charge is 12:1. In this manner, 24 Joules would be the distinction in potential vitality for 2 Coulombs of charge.

And the devices which are used to maintain the condition in an electric circuit are cells and batteries.