How does a potentiometer compare emf of two cells?
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.
Can potentiometer measure emf?
Potentiometer is a device used to measure the emf of the cell, potential difference across two terminals, unknown resistance, and internal resistance of the cell.
What is potentiometer experiment?
In a potentiometer experiment, it is found that no current passes through the galvanometer when the terminals of the cell are connected across 52cm of the potentiometer wire. If the cell is shunted by a resistance of 5Ω, a balance is found when the cell is connected across 40cm of the wire.
How will you compare the emf of two primary cells using potentiometer explain with proper circuit diagram?
Take out a 2,000 ohms plug from the resistance box (R.B.). Press the jockey at the zero end and note the direction of deflection in the galvanometer. Press the jockey at the other end of the potentiometer wire. If the direction of deflection is opposite to that in the first case, the connections are correct.
Why do we prefer potentiometer for measuring emf of a cell?
The potentiometer is preferred over voltmeter when there is a measurement of emf of the cell because the potentiometer does not draw any current as it is a null device. This is the reason why potentiometer is preferred over voltmeter in order to get the actual measurement of emf.
What is the difference between potentiometer and emf?
Potentiometer and voltmeter both measure voltage. The significant difference between the two is that a potentiometer measures the emf of the circuit while voltmeter measures the end terminal voltage of the circuit. A potentiometer is a three-terminal device that measures unknown voltage source with a known voltage.
Why is a calibrated potentiometer used to measure emf?
A potentiometer is preferred (ahead of voltmeter) when measuring the e.m.f of a cell because it uses the concept of null point to practically draw zero current from the cell. This is not the case with a voltmeter which can draw some current from the cell.
How can a potentiometer be used to determine the internal cell?
To calculate internal resistance, we use a potentiometer to first calculate the voltage across the battery, with no current through it. Then we attach a resistor in parallel to the battery and recalculate the voltage across it.
What is the use of two way key in potentiometer?
The two primary cells whose emfs are to be compared, are so connected in the circuit that their positive terminals are joined together to the end A of the potentiometer wire AB and their negative terminals are joined to a galvanometer through a two-way key a, b, c.
What is the principle of potentiometer explain its use to compare the emf of two primary cells?
Therefore, a potentiometer is an instrument which is used to calculate the potential difference. It works on the principle that potential is directly proportional to its length. Potentiometer can be used to compare emf of two cells or calculate internal resistance for a cell.
Why do we prefer a potentiometer to measure emf of a cell rather than a voltmeter?
A voltmeter draws current from a cell, therefore voltmeter measure terminal potential difference rather than emf, while a potentiometer at balance, does not draw any current from the cell; so the cell remains in open circuit. Hence potentiometer reasds the actual value of emf.
Why do we prefer potentiometer to compare the EMFs of cells than a voltmeter?
How to comparision EMF using a potentiometer?
If E 1 and E 2 are the e.m.f s of the two given cells and l 1 and l 2 are the two balancing lengths respectively on the potentiometer then, A potentiometer with atleast 4 m wire, an ammeter, a galvanometer, a voltmeter, a resistance box, a jockey, sandpaper, a one way key, a Leclanche cell, a Daniell cell, a two way key and rormectine; wires
When to use the potentiometer to compare two cells?
It is also used for comparing the e.m.f s of two given cells. If E 1 and E 2 are the e.m.f s of the two given cells and l 1 and l 2 are the two balancing lengths respectively on the potentiometer then,
How is a potentiometer used in an experiment?
Experiment: To compare the e.m.f.’s of two given primary cells by using a potentiometer. A voltmeter is a device used for measuring the terminal potential difference of a cell. But in the process of measuring, it draws a small current from the cell.
How to compare EMF of two primary cells?
To compare the EMF of two given primary cells (Daniel and Leclanche cells) with the help of a potentiometer. Using a voltmeter it is possible to measure only the potential difference between the two terminals of a cell, but using a potentiometer we can determine the value of emf of a given cell.
