It is associate degree electronic element. it's applied in associate degree electronic circuit for adjusting circuit resistance to regulate voltage or current of that circuit or a part of that circuit. The electrical phenomenon is varied by slippery  a wiper contact on a resistance track. typically the resistance is adjusted at planned worth needed|as needed|pro re nata|PRN} at the time of circuit building by adjusting screw hooked up thereto and typically resistance is adjusted as once required by dominant knob connected thereto. The active resistance worth of the resistor depends upon the position of the slider contact on the resistance track.

It primarily consists of a resistance track and a wiper contact. The wiper contact moves on the resistance track once adjustable element is adjusted. There square measure primarily 3 differing kinds of resistance track utilized in this electrical device they're carbon track, cermet (ceramic and metal mixture) track and wire wound track. Carbon track and cermet track square measure used for top resistance application whereas wire wound track is employed for low resistance resistor. The resistance tracks usually square measure of circular form however straight track is additionally utilized in several cases.

It is used as a resistor once one finish of the resistance track and wiper terminal square measure connected to the circuit and alternative terminal of resistance track remains open. during this case the electrical phenomenon between connected terminal and wiper terminal depends upon the position of the wiper (slider) on the resistance track. A resistor also can be used as a potentiometer once each ends of the resistance track square measure connected to the input circuit and one amongst the same ends of resistance track and wiper terminal is connected to the output circuit. during this case all 3 terminals square measure in use. typically in physics circuit there could also be demand of adjustable resistance however this adjustment is needed just one occasion or fairly often. this is often done by connecting planned resistors within the circuit. planned electrical device is one quite resistor whose electrical phenomenon worth is adjusted by adjusting associate degree adjustable screw hooked up thereto.

Resistance track wise there square measure primarily 2 forms of resistance track offered one is linear track and alternative is exponent track. In linear track the resistance worth varies linearly with dynamic  slider position on the track. which means the resistance and therefore the position of slider, kind a line characteristics curve. once the resistance of resistor, varies logarithmically with position of the slider contact on the resistance track, the track is referred as exponent track.

The resistance worth and sort of track square measure marked on the electrical device itself. for instance once a resistor is marked as fiveK9 sculptor suggests that it's most 5.9 kg Ω resistance and contains a linear resistance track. once more once a electrical device is marked as 2M LOG, it'll have most two mega Ω resistance and it's exponent track. planned resistors square measure linear track kind.

But the variable resistors used for volume management in electronic equipment square measure primarily LOG kind as our ears have exponent response to the loudness. In GOL electrical device, the resistance changes slowly at starting and apace at towards finish of the track.

A resistor is used primarily in 2 other ways. once one finish of resistance track and wiper terminal is connected with circuit then current through the electrical device limits in keeping with the position of the wiper contact on the resistance track. because the wiper contact slides off from the connected finish of the resistance track, the resistive worth of the electrical device will increase and current goes down through the circuit. which means the resistor behaves sort of a resistor.

Another use is as potentiometer. during this case the 2 ends of resistance track square measure connected with a voltage supply. therefore dip across the resistance track is up to the worth of voltage supply. currently the output or load circuit is connected across one finish of the resistance track and wiped terminal. therefore voltage across the load terminals is that the fraction of supply voltage and it depends upon the position of the wiper terminals on the resistance track. this is often another wide used application of variable resistors. this is often unneeded to mention, potentiometers square measure accustomed management voltages whereas rheostats square measure accustomed management electrical currents.

This is small version of resistor. planned resistors square measure directly mounted on circuit card and adjusted only the circuit is constructed. there's associate degree adjustable screw hooked up to the electrical device and alittle screwdriver is needed to regulate this screw for desired resistance worth. These resistors square measure quite cheaper than normal resistor offered within the market.