Explain the different conditions when an external potential is applied in the opposite direction in a galvanic cell (Voltaic cell) by taking a suitable cell example.

(N/A) Condition-$I$: (Condition in which the flow of current continues through the galvanic cell or $E_{\text{ext}} < 1.1 \ V$): According to diagram-$(a)$,if an external opposite potential is applied to the galvanic cell and increased slowly,we find that the reaction continues to take place until the opposing voltage reaches the value $1.1 \ V$. The redox reaction continues in the forward direction and the reaction does not stop.
$(b)$ Condition-$II$: (Condition in which the galvanic cell is stopped or $E_{\text{ext}} = 1.1 \ V$): According to diagram-$(b)$,when the external potential reaches $1.1 \ V$,the reaction stops altogether and no current flows through the cell. Any further increase in the external potential starts the reaction in the opposite direction (electrolytic cell).
$(c)$ Condition-$III$: (Condition in which the cell acts as an electrolytic cell or $E_{\text{ext}} > 1.1 \ V$): If the external potential is increased beyond $1.1 \ V$,the reaction proceeds in the reverse direction,and the cell acts as an electrolytic cell. Electrons flow from the copper electrode to the zinc electrode,and current flows from the zinc electrode to the copper electrode.