The Potentiometer is an electric instrument used to gauge the EMF (electromotive power) of a given cell, the inward obstruction of a cell. And furthermore it is utilized to think about the EMFs of various cells. It can likewise use as a variable resistor in a large portion of the applications. These potentiometers are utilized in enormous amounts in the production of hardware gear that gives a method of changing electronic circuits so the right yields are acquired. Despite the fact that their most clear utilize must be for volume controls on radios and other electronic gear utilized for sound.
For what reason is Potentiometer picked over Voltmeter to gauge the potential (EMF) of a cell? At the point when we use Voltmeter, current courses through the circuit, and on account of the inward opposition of the cell, consistently terminal potential will be not exactly the genuine cell potential. In this circuit, when the potential contrast is adjusted (utilizing a Galvanometer invalid identification), no current streams in the circuit, so the terminal potential will be equivalent to the real cell potential. So we can comprehend that the Voltmeter gauges the terminal capability of a cell, yet this estimates genuine cell potential. The schematic images of this is demonstrated as follows:
Development and Working Principle
The potentiometer comprises of a long resistive wire L comprised of magnum or with constantan and a battery of known EMF V. Interface the two finishes of the resistive wire L to the battery terminals as demonstrated as follows; let us accept this is an essential circuit game plan. One terminal of another cell (whose EMF E is to be estimated) is toward one side of the essential circuit and another finish of the cell terminal is associated with any point on the resistive wire through a galvanometer G. Presently let us expect this plan is an auxiliary circuit. The plan of the potentiometer as demonstrated as follows.
The essential working standard of this depends on the way that the fall of the potential over any part of the wire is straightforwardly relative to the length of the wire, if wire has a uniform cross-sectional zone and the steady flow coursing through it.”When there is no possible contrast between any two hubs there is electric flow will stream”.
Presently the potentiometer wire is really a wire with high resistivity (ῥ) with uniform cross-sectional zone A. Along these lines, all through the wire, it has uniform opposition. Presently this potentiometer terminal associated with the phone of high EMF V (disregarding its inward obstruction) called driver cell or the voltage source. Let the current through the potentiometer is I and R is the all out obstruction of the potentiometer.
A potentiometer is additionally usually known as pot. These potentiometers have three terminal associations. One terminal associated with a sliding contact called wiper and the other two terminals is associated with a fixed obstruction track. The wiper can be moved along the resistive track either by utilization of a straight sliding control or a revolving “wiper” contact. Both rotating and straight controls have a similar fundamental activity.
The most well-known type of potentiometers is the single turn revolving potentiometer. This kind of potentiometer is frequently utilized in sound volume control (logarithmic shape) just as numerous different applications. Various materials are utilized to develop potentiometers, including carbon piece, cermet, conductive plastic, and the metal film.