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The emf (electromotive force) of a cell is
AAlways larger than V across a closed circuit minus internal resistance loss
BIndependent of the chemistry of the cell
CThe potential difference across its terminals when current is being drawn
DThe potential difference between its terminals in an OPEN circuit (no current flowing)
Answer & Solution
Correct answer: D. The potential difference between its terminals in an OPEN circuit (no current flowing)
EMF ε is the open-circuit terminal potential. When current I flows through internal resistance r, the terminal voltage drops to V = ε − Ir.
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