Potentio Meter

A potentiometer is a three-terminal resistor with a sliding contact that forms an adjustable voltage divider. If only two terminals are used (one side and the wiper), it acts as a variable resistor or Rheostat. Potentiometers are commonly used to control electrical devices such as a volume control of a radio. Potentiometers operated by a mechanism can be used as position transducers, for example, in a joystick.
Potentiometers are rarely used to directly control significant power (more than a watt). Instead they are used to adjust the level of analog signals (e.g. volume controls on audio equipment), and as control inputs for electronic circuits. For example, a light dimmer uses a potentiometer to control the switching of a TRIrAC and so indirectly control the brightness of lamps.
Potentiometers are sometimes provided with one or more switches mounted on the same shaft. For instance, when attached to a volume control, the knob can also function as an on/off switch at the lowest volume. potentiometer (colloquially called a "pot") is constructed using a semi-circular resistive element with a sliding contact (wiper). The resistive element, with a terminal at one or both ends, is flat or angled, and is commonly made of graphite, although other materials may be used instead.
The wiper is connected through another sliding contact to another terminal. On panel pots, the wiper is usually the center terminal of three. For single-turn pots, this wiper typically travels just under one revolution around the contact. "Multiturn" potentiometers also exist, where the resistor element may be helical and the wiper may move 10, 20, or more complete revolutions, though multiturn pots are usually constructed of a conventional resistive element wiped via a worm gear. Besides graphite, materials used to make the resistive element include resistance wire, carbon particles in plastic, and a ceramic/metal mixture called cermet.