Question

A reversible galvanic cell is connected to an external battery. If the electric potential of the battery is less than the electric potential of the galvanic cell, then the current:

• A.
  Will not pass through the circuit
• B. Will flow from battery to the galvanic cell
• C. Will flow from galvanic cell to the battery
• D. Can flow in any direction

Answer 1

The correct option is C Will flow from galvanic cell to the battery

The effect of opposing potential applied to galvanic cell as follows,

1. $E_{external}<E_{cell}$
If an external opposing potential is lower than electrical potential of the cell, the normal reactions of the cell will occur and the electrons will flow from anode to cathode. Hence, the current will flow from galvanic cell to battery

2. $E_{external}=E_{cell}$
When the external voltage is equal to the electrical potential of the cell, there will be no flow of electrons or current. Also, no chemical reaction.

3. $E_{external}>E_{cell}$
If an external opposing potential is higher than electrical potential of the cell, the reaction begins to take place in the opposite direction i.e., non-spontaneous process starts.
Thus, the current will flow from battery to galvanic cell.
Here, anodic ions begins to deposit on anode and cathode metal begins to deteriorate.