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Question
The instrument which can measure terminal potential difference as well as electromotive force (e.m. f.) is ______
- Wheatstone’s meter bridge
- Voltmeter
- Potentiometer
- Galvanometer
Solution
(c) Potentiometer
A potentiometer is an instrument used to compare the e.m.f. of two cells or any two sources of e.m.f. If the e.m.f. of one of the sources is known, then the absolute value of the other source can be determined. The potentiometer can also be used to determine the internal resistance of a cell, to measure current, to calibrate an ammeter or voltmeter, to compare resistances, and for measurement of thermoelectric e.m.f.
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