Gaseous Discharge Lamps

Are members of the electric discharge family of light sources . Light is produced when a high-pressure electric arc is passed through a gas vapos, rather than by a low-pressure arc as in fluorescent lamps.

Unit of light (or luminous flux)

The amount of lumens falling on an area one square foot one foot away

Used to measure the density of the luminous flux

One footcandle is equivalent to

Unit of light intensity in English System

Unit of brightness

Unit measure of luminous intensity

Composed basically of a sealed glass containing a filament

Complete optical systems in a single bulb. The bulb contains a filament, reflector and lens

Have an internal reflector that throws all of the light out the front of the lamp

sometimes called pressed reflector, made of two glass parts; one is the reflector welded together. Sometimes aimed into a tight beam designed to hit a specific object or a smaller surface area. designated as 'spot'

Also called 'quartz' or 'quartz-iodine'. Hotter-burning incandescent lamps. These laps use a halogen gas cycle to prevent rapid depreciation

Comprises a cylindrical glass tube, sealed at both end and containing an inert gas usually argon and mercury vapors

Are the first HID lamps to be developed. Produces visible light of characteristically Blue green color. Suitable only for limited industrial areas, general outdoor applications and street lighting

Newest addition to the HID field. It is the most efficient of the HID lamps

Provides a desired bright, white, colored and long-lasting light. Ideal for retail, feature lighting, ceiling fixture, cove lighting, etc.

It limits the amount of current in the lamp and provides proper starting voltages

Used where color matching is important; not in general use because of high proportion of blue

Combines high efficiency with good color rendering; used in factories, offices, schools, rather cold in appearance

Most efficient lamp; suitable for homes, restaurants, hotels

A device which supports the source or sources of electric light and redirects or helps to control the light rays form the source.

Distributes light equally in all directions; direct and reflected glare present; space pleasant

Characterized by high utilization of filters in work plane, high contrast with surroundings, sharp shadows, and direct and reflected glare

Eliminates high contrasts, brightening of upper portion makes room larger and pleasant

Provides good brightness control in the lower hemisphere and reasonable freedom from shadows

Greatest control of brightness, efficient utilization of light depends absolutely on reflection factor for ceiling and upper sidewalls

A system where light sources are shielded by a panel parallel to the wall and attached to the ceiling to distribute light downwards over the wall. Considered as direct lighting

A system where light sources are shielded by ledge to distribute light upwards over the ceiling and upper wall. Considered as indirect lighting

A system where light sources are shielded by ledge to a panel parallel to the wall usually across the top of the window. This provides light both upwards and downwards over the wall

Lighting method which employs lamps at definite points depends on the position of furniture or the position of activity areas

Lighting method that strives for diffused light and uniform intensity over an entire area.

Lighting method that provides sufficient general lighting to illuminate various objects in the room at the same time furnishes additional local lamps at desks

Lighting method that for the atmosphere and interest when activities do not require much light

A complete lighting fixture, including lamps

a false ceiling of diffusing material with light sources mounted above

Quantitative measure of brightness of a light source

a tubular fluorescent lamp with a disc base at each end

Amount of light falling on a surface; a measure of light flux density

Method used for calculating illuminance levels in uniform situations; also called zonal cavity method

Loss of light when light rays strikes or traverses any medium

The ratio of light absorbed by a material to the light falling upon it is called

An electric component which consists of conducting plates insulated form each other by a layer of dielectric material

A system for cataloging colors based on the smallest discrete increment of color change recognizable by a human.

The data that describes the ebam characteristics of a lamp or lamp fixture

The ratio of light reflected by a surface to the light falling upon it

The process by which light is bent when passing from one medium to another

The passage of light through a medium when light falls upon a transparent material. It is refracted or bent as it passes through the material

A beam of light is specularly reflected when a light ray striking a shiny or glossy surface at an angle of incidence; a reflection that retains the original image