Potentiometers are variable resistance devices. A change in the linear or angular displacement of a potentiometer varies the effective length of its conductor, and therefore the resistance of the device. This change in resistance can be related to the displacement through a change in output voltage. Potentiometers have a tendency for nonlinearity, and care must be taken when a high degree of accuracy is required. Trimmer potentiometers are often built into the circuit to adjust the maximum and minimum output voltage to correspond to the maximum and minimum displacements of the measurement potentiometer
 

The potentiometric pressure sensor provides a simple method for obtaining an electronic output from a mechanical pressure gauge. The device consists of a precision potentiometer, whose wiper arm is mechanically linked to a Bourdon or bellows element. The movement of the wiper arm across the potentiometer converts the mechanically detected sensor deflection into a resistance measurement, using a Wheatstone bridge circuit
  The mechanical nature of the linkages connecting the wiper arm to the Bourdon tube, bellows, or diaphragm element introduces unavoidable errors into this type of measurement. Temperature effects cause additional errors because of the differences in thermal expansion coefficients of the metallic components of the system. Errors also will develop due to mechanical wear of the components and of the contacts.
  Potentiometric transducers can be made extremely small and installed in very tight quarters, such as inside the housing of a 4.5-in. dial pressure gauge. They also provide a strong output that can be read without additional amplification. This permits them to be used in low power applications. They are also inexpensive. Potentiometric transducers can detect pressures between 5 and 10,000 psig (35 KPa to 70 MPa). Their accuracy is between 0.5% and 1% of full scale, not including drift and the effects of temperature.