A potentiometer is a NULL device used to:
AGenerate voltage
BCompare EMFs accurately without drawing current
CMeasure resistance
DStore charge
Answer & Solution
Correct answer: B. Compare EMFs accurately without drawing current
Potentiometer compares emf of an unknown source with a standard, achieving balance by adjusting a slider — drawing NO current from the unknown source at balance. Hence measures true emf, not terminal voltage.
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