LIGHT_VOCABULARY

=**General Electrics**=

An auxiliary piece of equipment required to start and to properly control the flow of current to gas discharge light sources such as fluorescent and high intensity discharge (HID) lamps. Typically, magnetic ballasts (also called electromagnetic ballasts) contain copper windings on an iron core while electronic ballasts are smaller and more efficient and contain electronic components.
 * Ballast**


 * Cathode**

Metal filaments that emit electrons in a fluorescent lamp. Negatively charged free electrons emitted by the cathode are attracted to the positive electrode (anode), creating an electric current between the electrodes. A ratio expressing the luminous efficacy of a light source. Typical lamp efficacies: Note: The values above for discharge lamps do not include the effect of the ballasts, which must be used with those lamps. Taking ballast losses into account reduces "system" or lamp-ballast efficacies typically by 10-20% depending upon the type of ballast used.
 * Lumens/Watts**
 * Thomas Edison's first lamp - 1.4 lpW
 * Incandescent lamps - 10-40
 * Halogen incandescent lamps - 20-45
 * Fluorescent lamps - 35-105
 * Mercury lamps - 50-60
 * Metal halide lamps - 60-120
 * High-pressure sodium lamps - 60-140

=**Pegasus Associates Lighting**=

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 * Accent Lighting:** lighting that is used to accent or highlight a particular object such as a work of art. To be effective accent lighting should be approximately four or five times the level of ambient light in the room, area, or space. House plants can be accented by aiming an uplight at the wall behind the plant, creating a dramatic silhouette of the plant against the wall. To learn more about this topic click [|Accent Lighting].=====

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 * Ballast:** an electrical device used with [|fluorescent] and [|HID] (high intensity discharge) lamps (light bulbs) to supply sufficient [|voltage] to start and operate the lamp but then to limit the current during operation=====

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 * Cathode**: an electrode that emits electrons. A [|fluorescent lamp] cathode emits or discharges electrons to the cathode at the other end of the lamp (light bulb).=====

**Lumen:** a unit of measure used to describe the amount of light that a light source produces or emits. For reference please consult the table below.

 * ~ =====INCANDESCENT LAMP WATTAGE===== ||~ =====APPROX. LUMENS===== ||  ||~ =====INCANDESCENT LAMP WATTAGE===== ||~ =====APPROX. LUMENS===== ||
 * =====4W===== || =====20 lumens===== ||^  || =====60W===== || =====615 lumens===== ||
 * =====7W===== || =====45 lumens===== ||^  || =====75W===== || =====960 lumens===== ||
 * =====10W===== || =====56 lumens===== ||^  || =====100W===== || =====1100 lumens===== ||
 * =====15W===== || =====95 lumens===== ||^  || =====150W===== || =====2850 lumens===== ||
 * =====25W===== || =====232 lumens===== ||^  || =====200W===== || =====3800 lumens===== ||
 * =====40W===== || =====360 lumens===== ||^  || =====300W===== || =====6280 lumens===== ||
 * =====NOTE: These [|lumen] values are approximate because they can vary with the manufacturer of the lamp, the age of the lamp, the dirt on the lamp, whether the lamp is clear or frosted, the voltage rating of the lamp, and the exact voltage of the circuit.===== ||