Question:

A variable, the opposite external potential (\(E_{ext}\)) is applied to the cell \(\mathrm{Zn \mid Zn^{2+}\ (1\ M) \parallel Cu^{2+}\ (1\ M) \mid Cu}\), of potential 1.1 V. When \(E_{ext} \lt 1.1\) V and \(E_{ext} \gt 1.1\) V, respectively electrons flow from

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If the opposing potential is below the cell emf the cell still works as a galvanic cell; above it, the cell is driven in reverse.
Updated On: Nov 11, 2026
  • anode to cathode in both the cases.
  • anode to cathode and cathode to anode.
  • cathode to anode and anode to cathode.
  • cathode to anode in both cases.
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The Correct Option is B

Solution and Explanation

For \(E_{ext} \lt 1.1\) V the cell reaction \(\mathrm{Zn + Cu^{2+} \rightarrow Zn^{2+} + Cu}\) still proceeds: electrons flow from Zn (anode) through the external circuit to Cu (cathode), i.e. anode to cathode.
For \(E_{ext} \gt 1.1\) V the external source overcomes the cell and the reaction is reversed (electrolytic action): electrons flow from Cu to Zn, i.e. from the cathode to the anode of the original cell.
Answer: (2) anode to cathode and cathode to anode.
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