Resistors

Resistors are passive electronic components which consume but do not generate power. They are added to a circuit where they complement active components like micro controllers and other integrated circuits. They are commonly used to limit current, divide voltage and pull-up I/O lines; they have a specific, never-changing resistance. Resistors are a variety of shapes and sizes and their resistance is affected by three factors: the length, the diameter and the cross-sectional area of the wire. There are two termination types, one of which is through-hole. It has long pliable leads which can be stuck into a breadboard or hand-soldered. The second is the surface-mount resistor which has tiny black rectangles which are set by robots. There are special resistor packages which are pre-wired packs of five or so resistor arrays which share a common pin or are voltage dividers. Resistors are used in many electronic devices. A variable resistor is used to turn the volume down by turning up the resistance in the circuit that drives the loudspeaker of televisions or audio equipment. As a voltage divider, the resistor circuit can turn a larger voltage into a smaller one. Another application is in LED current limiting which prevents explosions in the series.