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Flashcards in test 2 - lighting Deck (20):
1

physics of light

color is determined by wavelength - longest is red (infrared), shortest is violet or (ultraviolet, UV)
light travels at 186,000 miles per second

2

luminous transmittance

measure of capability to transmit incident light

3

specular reflection

reflection that occurs on smooth surface such as polished glass or stone

4

luminous intensity

measured in candela (candlepower)
represents the force that generates the light that we see

5

luminous flux

measured in lumens
source that radiates light equally in all directions and surrounds it with a transparent sphere of 1m

6

illuminance

one lumen of luminous flux produces an illuminance of 1 lux - density of luminous power
lux = lumens / sq meter area

7

brightness

the impression received of an object

8

luminance

measurable, reproducible state of an object

9

inverse square law

illumination on the larger sphere is inversely proportional to the ratio of the sphere area
lux2/lux1 = area1/area2

10

the eye

cone - responsible to discriminate details, color
rod - peripheral, motion sensitive

11

target foot candle levels

depends on contrast, size, reflectance, importance of speed and accuracy, and exposure time
if 50% or more of occupants are more than 65 years old, illuminance recommendations are doubled

12

black body

light absorbing body - when heated glows deep red then orange then finally blue-white

13

color constancy

space lit by colored light where the eye adapts to recognized specific colors

14

efficacy

photometric efficiency- ability to produce an effect
the ratio of lumens provided to watts of heat produced by a source
unit: lumens/watt

15

indirect lighting

90-100% output is directed toward ceiling and upper walls

16

semi-indirect lighting

60-90% is directed upward to ceiling and upper walls

17

semi-direct lighting

60-90% is directed downward

18

direct lighting

all light is directed downward

19

diffused lighting

equal distribution of light

20

uniformity of illumination

any space that is intended to be lighted uniformly must establish a ceiling fixture spacing that gives uniformity of illumination
ratio of max to minimum illuminance on working plane is 1:1.3 - for general circulation lighting it can go up to 1.5