test 2 - lighting Flashcards
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
luminous transmittance
measure of capability to transmit incident light
specular reflection
reflection that occurs on smooth surface such as polished glass or stone
luminous intensity
measured in candela (candlepower)
represents the force that generates the light that we see
luminous flux
measured in lumens
source that radiates light equally in all directions and surrounds it with a transparent sphere of 1m
illuminance
one lumen of luminous flux produces an illuminance of 1 lux - density of luminous power
lux = lumens / sq meter area
brightness
the impression received of an object
luminance
measurable, reproducible state of an object
inverse square law
illumination on the larger sphere is inversely proportional to the ratio of the sphere area
lux2/lux1 = area1/area2
the eye
cone - responsible to discriminate details, color
rod - peripheral, motion sensitive
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
black body
light absorbing body - when heated glows deep red then orange then finally blue-white
color constancy
space lit by colored light where the eye adapts to recognized specific colors
efficacy
photometric efficiency- ability to produce an effect
the ratio of lumens provided to watts of heat produced by a source
unit: lumens/watt
indirect lighting
90-100% output is directed toward ceiling and upper walls
