How can potentiometer be used to measure emf?

How can potentiometer be used to measure emf?

Using a potentiometer, we can determine the emf of a cell by obtaining the balancing length l. Here, the fall of potential along the length l of the potentiometer wire is equal to the emf of the cell, as no current is being drawn from the cell. Then, or, ; where k is the potential gradient along the wire.

Why potentiometer can measure emf of a cell?

A voltmeter has a finite resistance and draws current from a cell ,therefore voltmeter measures terminal potential difference rather than emf,while a potentiometer at balance condition,does not draw any current from the cell;so the cell remains in open circuit. Hence potentiometer reads the actual value of emf.

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What is potentiometer and explain how it can be used to measure the emf of cell with the help of diagram?

Potentiometer is a device used to measure the internal resistance of a cell, to compare the e.m.f. of two cells and potential difference across a resistor. It consists of a long wire of uniform cross sectional area and of 10 m in length.

What is potentiometer is used to measure?

A potentiometer is an instrument which is used for measurement of potential difference across a known resistance or between two terminals of a circuit or network of known characteristics. A potentiometer is also used for comparing the emf of two cells.

What is difference between potentiometer and emf?

Key Differences: The Potentiometer is an instrument used for measuring the emf, whereas the voltmeter is a type of meter which measures the terminal voltage of the circuit. The Potentiometer accurately measures the potential difference because of zero internal resistance.

Why do we prefer a potentiometer with longer wire?

A potentiometer with a longer bridge wire is preferred because such potentiometer will have a small potential gradient making it more sensitive.

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What is the working of potentiometer?

Potentiometers work by varying the position of a sliding contact across a uniform resistance. In a potentiometer, the entire input voltage is applied across the whole length of the resistor, and the output voltage is the voltage drop between the fixed and sliding contact as shown below.

What is the formula of EMF of cell?

Internal resistance of a cell. This shows that we can calculate the EMF if we know the voltage across the terminals, the current flowing and the internal resistance of the cell….The Formula for Calculating the EMF.

\varepsilon electromotive force
Q Charge of the circuit.

Can a potentiometer measure the emf of a cell?

In this laboratory exercise, we will use the concept of the zero current draw of the potentiometer to measure the Emf of a cell. A voltmeter, because it must draw some current, measures only terminal voltage of a cell. The potentiometer, however, is able to measure the true Emf of the cell.

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How is a potentiometer used to measure electromotive force?

A potentiometer is also used to measure the electromotive force of a cell. It is possible to compare the emf of two cell with a potentiometer. It can be used to measure the internal resistance of the cell.

How is voltage measured in a potentiometer circuit?

The potentiometer measures voltage by comparing the measuring voltage with voltage across the resistance of the potentiometer. So for operation of potentiometer there must be a source voltage connected across the potentiometer circuit. This cell to provide this source voltage to drive the potentiometer is called driver cell.

Is the potentiometer used to measure internal resistance?

Potentiometer Construction, Working and Applications. The Potentiometer is an electric instrument that used to measure the EMF (electro motive force) of a given cell, the internal resistance of a cell.