Electrolytic cell:
Consider the electrolytic cell display in Figure. A voltage Eapplied is applied to the cell in like a way that a current flows by the cell. While Eapplied > Ecell, there will be a flow of current in the circuit. While there is a current, the potential of the cell is less than the thermodynamic potential since one or one of the following phenomena is operating: IR drop, concentration polarisation and kinetic (chemical) polarisation.
Figure: An electrolytic cell