Ch. 3

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  1. Brightness
    subjective sensation that occurs in conciousness of a human behavior
  2. Luminance
    objective measurement of intensity per unit of projected area
  3. Luminaire (lighting fixture)
    emits light downward, upward, or multidirectional and concentrated or diffuse
  4. Glare
    is a bright light which can interfere with visual perception
  5. Diffuse Light
    a distribution of light that is dispersed in a wide pattern and not incident from any particular direction
  6. Direct/Indirect
    light emitted in a downward and upward direction, with little or no light emitted at angles near the horizontal
  7. Cutoff
    measured up from the nadir (straight down 0 degree angle), the angle of the first line of sight at which the care light source is not visible
  8. Downlight
    a recessed surface mounted, or pendant-mounted luminaire which emits light in a downward direction with no upward component
  9. Indirect
    an upward distribution of light which produces illumination on the horizontal workplane via reflection from the ceiling and upper walls
  10. Grazing Light
    from luminaires located close to a surface being lighted, strengthens highlight and shadows
  11. What is grazing light used for?
    inspection to detect surface blemishes and errors in workmanship
  12. What is grazing light appropriate for?
    lighting heavily textured surfaces such as rough plaster, masonry, or concrete; disastrous for flat walls of smooth plaster or gypsum board
  13. Visual Comfort Probability
    rating is defined as the percentage of people who, if seated in the least desirable location in an office work space, will find a lighting installation comfortable.
  14. Reflected Glare
    excessive uncontrolled luminance reflected from objecs or surfaces in the field of view
  15. Two additional lighting problems that cause concern for VDT users:
    • 1) proper lighting for the non-VDT tasks the worker must also perform
    • 2) lighting of the area in the worker's field of view
Card Set
Ch. 3
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