How Potentiometer works

A potentiometer is a resistive sensor used to measure linear displacements as well as rotary motion. In a potentiometer an electrically conductive wiper slides across a fixed resistive element. A voltage is applied across the resistive element. Thus a voltage divider circuit is formed. The output voltage(Vout) is measured as shown in the figure below. The output voltage is proportional to the distance travelled.
There are two types of potentiometer, linear and rotary potentiometer. The linear potentiometer has a slide or wiper. The rotary potentiometer can be a single turn or multi turn.

The important parameters while selecting a potentiometer are
•Operating temperature
•Shock and vibration
•Humidity
•Contamination and seals
•life cycle
•dither

Some of the advantages of the potentiometer are
•Easy to use
•low cost
•High amplitude output
•Proven technology
•Easily available

Some of the disadvantages of the potentiometer are
•Since the wiper is sliding across the resistive element there is a possibility of friction and wear. Hence the number of operating cycles are limited.
•Limited bandwidth
•Inertial loading

Some of the applications of the potentiometer are
•Linear displacement measurement
•Rotary displacement measurement
•Volume control
•Brightness control
•Liquid level measurements using floats
  

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