The principle of a potentiometer is that the potential dropped across a segment of a wire of uniform cross-section carrying a constant current is directly proportional to its length. Measurement potentiometers are divided into four main classes listed below.ĭial potentiometer, with built-in galvanometer and reference voltage source This null balance measuring method is still important in electrical metrology and standards work and is also used in other areas of electronics. At that point the galvanometer draws no current from the unknown source, and the magnitude of voltage can be calculated from the position of the sliding contact. The deflection of the galvanometer is observed and the sliding tap adjusted until the galvanometer no longer deflects from zero. The sliding contact or wiper of the potentiometer is adjusted and the galvanometer briefly connected between the sliding contact and the unknown voltage.

In this arrangement, a fraction of a known voltage from a resistive slide wire is compared with an unknown voltage by means of a galvanometer. The method was described by Johann Christian Poggendorff around 1841 and became a standard laboratory measuring technique. Since the reference voltage can be produced from an accurately calibrated voltage divider, a potentiometer can provide high precision in measurement. If a sensitive indicating instrument is used, very little current is drawn from the source of the unknown voltage. JSTOR ( December 2014) ( Learn how and when to remove this template message)Ī potentiometer is an instrument for measuring voltage or 'potential difference' by comparison of an unknown voltage with a known reference voltage.Unsourced material may be challenged and removed.įind sources: 'Potentiometer' measuring instrument – news Please help improve this article by adding citations to reliable sources. This article needs additional citations for verification.

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