A dimmer is a switch used to alter the brightness of a light by adjusting the amount of voltage it emits, using a mechanism known as a variable-voltage device. "Dimmer" itself is simply a generic term for any variable-voltage device used specifically for lighting. In addition to everyday household use, dimmers are frequently put to work for artistic effect in theatrical performances or in architectural lighting.
How Dimmers Work
Simple dimmers work by directing the flow of electricity into a long wire-like object known as a resistor, which works to repel the current being channeled. A simple dimmer set to a low-light level directs all incoming energy to the base of the resistor, which absorbs the flow and allows only a low amount of electricity to emerge from the other end into the fixture-resulting in a low-powered light.
By contrast, such a dimmer set for high-light allows the current to bypass much of the path through the resistor, resulting in a less-diluted flow and hence a brighter bulb. While an efficient means of varying light levels, this simple form of dimmer is an energy hog, intentionally dissipating extra electricity instead of restricting its flow. It also has an unfortunate tendency to overheat due to excess energy absorption.
For this reason, more advanced dimmers use semiconductors, which work to switch the flow of energy to the bulb off and on as needed, with a dimmer set to high-light channeling a steady flow of energy and those set to low-light channeling a more choppy flow, which is then synchronized by the dimmer into a constant but weaker current. Such dimmers are far more energy-efficient and less prone to catch fire, but on occasion can produce an unpleasant buzzing effect within the light fixture itself, due to the irregular flow of energy being admitted.
Types of Dimmers
Dimmers come in a variety of forms, with a standard dimmer that can process 600 watts and nonstandard dimmers of 800-1500 watts. Dimmers can be adjusted either by vertical switches or dials, and can be used for three-way lighting setups (in which a light is controlled by more than one switch) just as with regular light switches.
In addition, dimmers can be affixed to lamps by running the lamp cord through a special cord dimmer. The lamp cord is then either stripped, exposing its wires, or the dimmer itself is allowed to puncture and feed off the wire still in the cord-either of which method will grant the dimmer access to the lamp's energy flow and allow the user to adjust the fixture's brightness as desired.