Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
45 Cards in this Set
- Front
- Back
|
visibility |
the quality or state of being perceivable bythe eye - a person's ability to distinguish details of an object against a background |
|
|
illuminance |
the amount of light falling on 1 square foot, one foot away from 1 candle is one foot candle or 1fc. (light that strikes a surface) |
|
|
efficacy |
- Lamp performance or efficiency ismeasured in the lamp lumens out put perWatt of energy - Measured in lumens per Watt (lm/W orLPW) |
|
|
Lamp |
term used to describe a device that transforms electricity into light, usuallyconsisting of a base, glass bulb and light emitting components |
|
|
Average Rated Life |
life span of a lamp, based on the statistical average time (in hours) when50% of a large group of lamps fail under specific test conditions |
|
|
Lamp Lumen Depreciation (LLD) |
• as a lamp ages and nears end of life, it produces less and less light • depreciation is caused by internal lamp component deterioration |
|
|
Correlated Colour Temperature (CCT) |
- represents the whiteness of a light measured in degrees Kelvin • typically visible light sources for interiors range from 2500°K to 5500°K • the higher the kelvin temperature the cooler (bluer) the source • the lower of the kelvin temperature the warmer (redder) the source |
|
|
Colour Rendering Index (CRI) |
• CRI rating is a percentage indicating how well a source renders thecolour appearance of objects • the poorer the colour rendition, the lower the CRI number• minimum acceptable CRI for interior applications is 80% |
|
|
Luminaire |
a complete lighting unit consisting of a lamp (or lamps) together with the partsdesigned to distribute the light, as well as the electrical parts required to generatethe light. |
|
|
Ballast |
a device to limit the current of an arc discharge lamp (fluorescent, metal halideand high pressure sodium sources) |
|
|
transformer |
a device which convert the voltage of a power source to an alternate voltage that is compatible with a light source |
|
|
driver |
a device to regulate the current of voltage of a LED light source |
|
|
circuits |
- part of the electrical distribution system in a building which is usually separately switched - circuits may be dedicated to specific uses (lighting, outlets, equipment) or geographic, serving a room or a floor |
|
|
current |
the measurement of electrical rate or flow expressed in amps, similar to the flow of water in a pipe |
|
|
voltage |
it is the measure of electrical force/ pressure in a circuit expressed in volts, which is similar to the pressure in a pipe |
|
|
wattage |
the measurement of electrical power consumed by lighting equipment, expressed in watts |
|
|
grazing |
- when light is directed at a surface from a very sharp, angle, nearly parallel - this effect enhances any variations on the surface depth, revealing texture |
|
|
Wallwashing |
when light is directed at a surface from a wide angle, flattening the roughness and making surfaces appear smoother |
|
|
silhouette |
when a light source is used not to illuminate an object itself but its background |
|
|
backlight |
placement of a light source behind an object |
|
|
uplight |
placement of a light source below an object or surface |
|
|
visual acuity |
- measure of a persons ability to distinguish fine details - 4 factors: size luminance, contrast and time |
|
|
size (visual acuity 4 factors) |
the larger and object the easier the critical detail of the object will be to see |
|
|
luminance (visual acuity 4 factors) |
- how bright an object or source appears - a term of photometric brightness - the imperial units of luminance are candelas per square foot - the metric units of luminance are candelas per square metre |
|
|
contrast (visual acuity 4 factors) |
the luminance difference between an object and it's background (ex black print on white) |
|
|
time (visual acuity 4 factors) |
given sufficient time, even small details can be seen under low levels of light su-consciously sacrificing speed and accuracy |
|
|
glare |
result of excessive, uncontrolled light within field of view |
|
|
reflected glare |
uncomfortable glare and reduced task visibility resulting from bright reflections from polished or glossy surface |
|
|
sparkle |
small points of high luminance can enhance visual interest "designed glare" |
|
|
shadows |
shadows interfere with task visibility or enhance definition of details by contrast |
|
|
luminance ratio |
- the ratio between the brightest and dimmest light levels within a space - these ratios create emphasis and highlight focal points |
|
|
horizontal illuminance |
- the amount of light falling onto a horizontal surface - typically the measured horizontal plane 30 inches high (0.76) |
|
|
vertical illuminance |
the amount of light falling onto a vertical surface |
|
|
lumens |
the unit of light output from a light source or luminaire |
|
|
efficacy |
- the capabilities of a lamp to transform electrical power into light - lumens per watt (lm/W) similar to miles per gallon - the higher the lm/W rating the more efficient the lamp is - all watts not transformed into light are expended as heat |
|
|
efficiency |
the ratio of lumens produced by the complete luminaire to the lumens produced by the bare lamps |
|
|
exitance |
the density of light leaving a surface |
|
|
uniformity |
- ratio of light and shadow on a surface - ratios are quantified as 'maximum to average' ; 'maximum to minimum' , 'medium to minimum' |
|
|
reflection |
specular reflection, spread reflection, diffuse reflection |
|
|
transmission |
l |
|
|
refraction |
l |
|
|
absorption |
the property of a material to reduce the amount of light reflected or transmitted |
|
|
concealment |
to hide the light source from normal viewing angles |
|
|
light pollution |
l |
|
|
light trespass |
l |
