About Potentiometer

1. Potentiometer is an instrument for measurement of an unknown
electromotive force (e.m.f.) or potential difference produced by
the flow of a known current in a network of circuits of known
characteristics. It is an instrument by which an unknown voltage
is measured by comparing it with a known voltage. The known
voltage may be supplied by a standard cell or any other known
voltage-reference source.
Potentiometers are used extensively in measurements where
I. Precision required is very high s compared to that can be
obtained by deflection instruments
II. It is important that no current be drawn from the source under
measurements
III. The current must be limited to a small value.
Advantages of Potentiometers:
I. It has very high accuracy because the result obtained does not
depend upon the actual deflection of a pointer, as is the case in
deflection instruments. Its result depends upon the accuracy with
which the voltage of the reference source is known.
II. It has no power consumption from the circuit containing
unknown e.m.f., when it is balanced.
III. The determination of voltage by Potentiometer is quite
independent of the source resistance.
Applications of Potentiometers:
I. Measurement of voltage.
II. Measurement of current.
III. Measurement of resistance.
IV. Measurement of power.
V. Calibration of ammeters, voltmeters and wattmeters.
There are two types of Potentiometers used in industry:

2. a) D.C. Potentiometers
b) A.C. Potentiometers