What is the principle of working of Potentiometer? Why don't we use voltmeter rathar than Potentiometer?
To reduce errors
If the constant current passing through the wire having uniform crossectional area the potential drop across any portion is drctly propnal to its length
We don't use voltmeter because it have itr own resistance due to which we can't get correct reading that's why we use potentiometer it have less or neglagible resistance with respect to voltmeter.
Potentiometer is a device having a wire of length10 m.it works on the principle of potential gradient.ie,V/l =k.so as length of the wire increases potential per unit length increases and can measure very small pd
Because voltmeter also draws some voltage and opposite to it potentiometer works on a null point method so that we can find e.m.f. of battery or cell accurate my.
We use voltmeter but when we have to do accurate measurements we use potentiometer as it helps us to measure very small values of PD.
Because in electronic devices circuits are very complicated . If then you must use several parameters for several circuits
If the constant current passing through the uniformly cross section al wire the potential drop across any portion of the wire is directly proportional to the length of the portion
It is a huge equipment so .....