The glass housing of an incandescent lamp, filled with an inert gas mixture, usually of argon and nitrogen, to retard evaporation of the filament

The threadlike conductor of an electric lamp that is heated to incandescence by the passage of an electric current

The emission of visible light by a body when heated to a high temperature

An incandescent lamp having a tungsten filament

A tungsten-halogen lamp having an infrared dichronic coating for reflecting infrared energy back to the filament, raising lamp efficiency, and reducing radiant heat in the emitted light beam

An incandescent lamp having a high percentage of its radiant power in the infrared region than a standard incandescent lamp, often having a red glass bulb to reduce the radiated visible light

An incandescent lamp having two filaments so that it can be switched to three successive degrees of illumination

A lamp designed for reduced energy consumption and a life longer than the conventionally set value for its general class

The standard rounded shape for the bulbs of general-service incandescent lamps

A flame-shaped bulb for the low-wattage, decorative incandescent lamps

A cone-shaped bulb for low-wattage, decorative incandescent lamps

A candle-shaped bulb for low-wattage, decorative incandescent lamps

A reflector bulb of blown glass for incandescent and high-intensity-discharge lamps, having an internal reflective coating and either a clear or frosted glass front to provide the desired beam spread

A parabolic aluminized reflector bulb cast glass for incandescent and high-intensity-discharge lamps, having a precisely formed internal reflector and a lensed front to provide the desired beam spread

An ellipsoidal reflector bulb for incandescent lamps, having a precisely formed internal reflector that collects light and redirects it into a dispersal pattern at some distance in front of the light source

An A bulb having a hemispherical, reflective silver bow opposite the lamp base to decrease glare

A globe-shaped bulb for incandescent lamps, having a low brightness for exposed use

A pear-shaped bulb for large incandescent lamps

A straight-sided bulb for low-wattage, decorative incandescent lamp

A multi-faceted reflector bulb for tungsten-halogen lamps, having highly polished reflectors arranged in discrete segments to provide the desired beam spread

A quartz bulb for tungsten-halogen lamps, similar in shape to the A bulb but having an angular profile

A tubular bulb for incandescent, fluorescent, and high-intensity-discharge lamps

A bulged tubular bulb for high-intensity-discharge lamps

An ellipsoidal bulb for high-intensity-discharge lamps

Electromagnetic radiation that the unaided human eye can perceive

The luminous flux emitted per unit solid angle by a light source, expressed in candelas

The intensity of light falling at any given place on a lighted surface, equal to the luminous flux incident per unit area and expressed in lumens per unit of area

The quantitative measure of brightness of a light source or an illuminated surface, equal to the luminous intensity per unit projected area of the source or surface viewed from a given direction

The SI unit of luminous flux, equal to the light emitted in a solid angle of one steradian by a uniform point source having an intensity of one candela

Luminous intensity expressed in candelas

The rate of flow of visible light per unit time, expressed in lumens

A unit of luminous intensity used prior to 1948, equal to the luminous intensity of a wax candle of standard specifications

The basic SI unit of luminous intensity

The SI unit of illumination, equal to one lumen per square meter

A unit of illumination on a surface that's everywhere one foot from a uniform point source of one candela and equal to one lumen incident per square foot

A unit of luminance or brightness equal to 0.32 candela per square centimeter

A unit of luminance or brightness equal to 0.32 candela per square foot

The sensation by which an observer is able to distinguish between differences in luminance

Impenetrable to light

Transmitting and diffusing light so that bodies on the opposite side are not clearly visible

Capable of transmitting light so that bodies situated beyond or behind can be distinctly seen

The striking of a ray of light or sound wave on a surface

The return of light, sound, or radiant heat after striking a surface

The change of direction of a ray of light as it passes obliquely from one medium into another in which its velocity is different

The modulation of light or sound waves as they bend around the edges of an obstacle in their path

The ratio of the radiation transmitted through and emerging from a body to the total incident on it, equivalent to one minus the absorptance

The ratio of the radiation absorbed by a surface to the total incident on the surface

The ratio of light or radiation reflected by a surface to that incident upon it, measured on a scale from zero for no reflecting power of a perfectly black surface to 1 for the perfect reflection of a white surface

The ratio of the radiation reflected by a surface to the total incident on the surface

Dispersed from an irregular surface

A scattered reflection of light from an irregular surface or an erratic dispersion through a translucent material

Directed from a smooth, polished surface