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Question
Why is potentiometer preferred over a voltmeter for comparison of emf. of cells?
Solution
Potentiometer is preferred over a voltmeter for comparison of emf of cells because of the following reasons:
(a) A potentiometer can measure the internal resistance of the cell, which a voltmeter cannot measure.
(b) A potentiometer can accurately measure small potential differences, which a voltmeter cannot.
(c) The accuracy of a potentiometer can also be increased by increasing the length of the wire, whereas the accuracy of the voltmeter is fixed.
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