Potentiometers standardisation Kisembo Academy

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This video is an explanation of how standardisation of potentiometers is done. • Thank you to those who fund me on • / kisemboacademy . You make it possible to produce these videos. • i get to teach you how to standardize potentiometer circuits. Standardizing a potentiometer simply refers to the process of finding the pd per unit length of the potentiometer. The slide wire in the potentiometer circuit has a uniform cross sectional area, and therefore a uniform resistance. The potential drop across the slide wire can be regulated by varying the driver current. The process of adjusting the driver current so that it matches with the potential drop of a certain portion of the slide wire is what we call the process of standardizing the potentiometer. • Transcript; • a slide wire in a potentiometer • has a uniform cross sectional area and • Therefore it definitely has a uniform resistance along its length • We can control the voltage drop along the slidewire by adjusting the amount of driver current that is moving out • the process of adjusting the driver current so that it matches with the voltage drop across a certain portion of • The sliding wire against a standard or a known reference source • Is what we are calling? • standardization of a potentiometer • Before we get into the details of standardization of a potentiometer circuit let us try and remind ourselves of a few • Key definitions that we need to keep in mind first of all what is an open circuit? • You remember I said that an open circuit or a cell is said to be in an open circuit • When there is no current flowing out of it • Then also a cell is said to be in a closed circuit • When some current has been drawn out of it so in reference to a potentiometer • We look at the potential difference. That is across the • balanced length in terms of • Being equivalent to a cell in either a closed circuit or a cell that is in an open circuit • we shall explore that a little bit later for now a • potentiometer consists of a mounted resistance where a b as we see • it is where we already stated that it has uniform cross sectional area and • This wire A-B can be of any length it can be a hundred • Centimeters it can be a hundred and twenty centimeters and so forth now • We said that the potentiometer has got what we call a primary car primary circuit and in the secondary circuit • the secondary circuit has got a galvanometer and • The balance condition of a potentiometer is when this galvanometer is • Deflecting zero there is no deflection on the government'll meaning that there is no current flowing through it • And it is at that point that the balance point along a bit • Is obtained when the balance point along a b is obtained in the potential difference across? • The point a and the balance point is equal to the potential difference across • the components in the secondary circuit • Now when a driver cell is connected to the slidewire at B this driver sells • It applies a uniform potential difference across the wire • so when solving • Problems that are involving potentiometers it means that • One key thing that we need to find fast is the PD per unit length of the wire • It could be PD per centimeter or PD per meter • So in an experiment where the potential difference pilot unit centimeter of the wire is obtained • We describe such an experiment as an experiment that is meant to • standardize all calibrated potentiometer • In an experiment whereby we seek to find the PD per unit length of a potentiometer wire • That experiment. We call it an • Experiment. That is meant to Standardize or calibrate a potentiometer • We're having a circuit here having grabbed a current Ip moving out and we're having a slight wire A-B there • So now this FB has got a potential across it V • This y remember is aware that has got uniform cross sectional area so it is if it's having a lead from cross-sectional area • It's it means it's having a uniform resistance along the entire length • So for us to get the PD per unit length of that entire wire • It's going to be the PD across FB • Divide that by the length of the wire so now if the length is 100 centimeters it means that we get the potential difference across • that length • divide that by the total length which is • which is 100 centimeters and so our answer will be in terms of volts per centimeter and • #Physicsmaths • #CurrentElectricity

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