Editing Resistor (section)

===Potentiometers===

[[File:Potentiometer cutaway drawing.png|thumb|Potentiometer with case cut away, showing parts: (''A'') shaft, (''B'') stationary carbon composition resistance element, (''C'') phosphor bronze wiper, (''D'') shaft attached to wiper, (''E, G'') terminals connected to ends of resistance element, (''F'') terminal connected to wiper.]]
A [[potentiometer]] (colloquially, ''pot'') is a three-terminal resistor with a continuously adjustable tapping point controlled by rotation of a shaft or knob or by a linear slider.<ref name="Mazda">{{cite book
 | last1  = Mazda
 | first1 = F. F.
 | title  = Discrete Electronic Components
 | publisher = CUP Archive
 | date   = 1981
 | pages  = 57–61
 | url    = https://books.google.com/books?id=3qk8AAAAIAAJ&pg=PA57
 | isbn   = 0521234700
 }}</ref>  The name ''potentiometer'' comes from its function as an adjustable [[voltage divider]] to provide a variable [[potential]] at the terminal connected to the tapping point.  Volume control in an audio device is a common application of a potentiometer.  A typical low power potentiometer ''(see drawing)'' is constructed of a flat resistance element ''<span style="color:red;">(B)</span>'' of carbon composition, metal film, or conductive plastic, with a springy [[phosphor bronze]] wiper contact ''<span style="color:red;">(C)</span>'' which moves along the surface.  An alternate construction is resistance wire wound on a form, with the wiper sliding axially along the coil.<ref name="Mazda" />  These have lower resolution, since as the wiper moves the resistance changes in steps equal to the resistance of a single turn.<ref name="Mazda" />

High-resolution multiturn potentiometers are used in precision applications.  These have wire-wound resistance elements typically wound on a helical mandrel, with the wiper moving on a helical track as the control is turned, making continuous contact with the wire.   Some include a conductive-plastic resistance coating over the wire to improve resolution.  These typically offer ten turns of their shafts to cover their full range. They are usually set with dials that include a simple turns counter and a graduated dial, and can typically achieve three-digit resolution. Electronic analog computers used them in quantity for setting coefficients and delayed-sweep oscilloscopes of recent decades included one on their panels.

<gallery mode=packed heights=160>
File:Potentiometer.jpg|Typical panel mount potentiometer
File:12 board mounted potentiometers.jpg|An assortment of small through-hole potentiometers designed for mounting on [[printed circuit board]]s.
</gallery>