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1. a device, such as a rheostat, for varying the current through an electric light and thus changing the illumination
a. a dipped headlight on a road vehicle
b. a parking light on a car
A solid-state device used to vary the voltage to a light fixture and thereby lower or raise the intensity of the light. Used mainly for incandescent lamps and fluorescent lamps with special ballasts. Also called a rheostat, it can be installed on a wall switch or directly into a lamp and can easily be added to existing installations.
An electrical or electronic control for varying the intensity of a lamp or other light source.
A device which varies the light intensity of a light source without appreciably affecting the spatial distribution of the light; usually an electric control device that varies the current flow and hence the light output of the lamp. dimmer room A room in which are located the dimmers for controlling the lights for an auditorium or theater.