A resistor is a passive two-terminal electrical component that implements resistance as circuit element. In electronic circuits, resistors are used to reduce current flow, adjust signal levels, divide voltages, bias active elements, and terminate transmission lines, among other uses. High-power can dissipate many watts of power heat, may be part motor controls, in distribution systems, or test loads for generators. Fixed have resistances only change slightly with temperature, time operating voltage. Variable elements (such volume control lamp dimmer), sensing devices light, humidity, force, chemical activity. Resistors common networks circuits ubiquitous equipment. Practical discrete components composed various compounds forms. also implemented within integrated circuits. The function specified by its resistance: commercial manufactured over range more than nine orders magnitude. nominal value the falls manufacturing tolerance, indicated on component.