The emf of a cell is equal to the potential difference across its terminals when:
Athe cell is short-circuited
Bno current is drawn from the cell
Cthe cell is fully discharged
Dmaximum current is drawn from it
Answer & Solution
Correct answer: B. no current is drawn from the cell
On open circuit I = 0, so terminal V = ε − Ir = ε. Once current flows, V = ε − Ir < ε.
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