In the old days if we wanted less light in a room we simply turn off a few lights or used a darker lamp shade to absorb the light. In modern times we use light dimmers to control the intensity of light. Light dimmer switches are electrical devices used to vary the intensity of a light. How they work is by decreasing or increasing the voltage with the dimmer switch. The light output will vary in intensity by reducing the power going to the light.

Dimmer light switches are used to control incandescent, halogen and compact fluorescent (CFL) light bulbs. However, more specialized equipment is needed to dim fluorescent lighting.

Light dimmer switches range in size from a small switch, the size of a normal light switch used in home lighting, to high power units used in large commercial buildings.

Modern dimmers are built from silicon-controlled rectifiers (SCR) instead of potentiometers or a variable resistor because they are more efficient. Older light dimmers are variable resistor which would dissipate power by heat. The dissipated heat causes the light switch to heat up. A silicon controlled rectifier light dimmer does not heat up.

Most modern residential light dimmer switches operate by sliding a knob on the switch face to change the brightness of the lights. The dimmers are small enough to fit into any regular electrical wall box used for switches. They are easy to install and are relatively inexpensive.

Modern light dimmers are actually thyristor dimmers. A thyristor light dimmer does not emit heat when the switch is turned to a lower setting therefore there is no wasted power as there is in the old variable rheostat light dimmers.

Light dimmer switches are a great convenience around the house because they can be used to vary the light intensity of a room, high for reading or low for watching television or setting a romantic mood.

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