Question

Why is a potentiometer preferred over a voltmeter for determining the e.m.f of a cell?

Answer 1

While a voltmeter draws a small current from the cell for its operation.So it measures the terminal p.d. in a closed circuit which is less than the emf of a cell.That is why apotentiometer is preferred over a voltmeter for measuring the emf of a cell.

Answer 2

$\textbf{Hey there}$!!

$\bold{Answer}$:

When a voltmeter is connected across the two poles of a cell, it draws a small current from the cell. As a result, the voltmeter measures terminal potential difference between the two poles of the cell, which is always less than e.m.f of the cell.

On the other hand, when a potentiometer is used for measurement of e.m.f of a cell, it does not draw any current from the cell. Hence, it measures e.m.f of the cell. For these reasons, a potentiometer is preferred over a voltmeter for measuring e.m.f of a cell.

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@karangrover12.