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Flashcards in Light Deck (38):
1

what is a standard candle measurement

amount of light given off from a standard candle. it's the most standard measure of intensity of a light source

2

what is a foot candle measurement

measure of the amount of light striking an area of 1 sq ft from one foot away

3

What is a luminous flux

the amount of light coming from a source, or the quantity of light emitted

4

what is the lumen unit

a unit used to specify the quantity of light required to illuminate 1 square food of reflective

5

what is used to measure lumens

a photographic light meter

6

what is a lambert

the brightness of a surface emitting or reflecting one lumen per square centimeter

7

darker colors absorb (more/less) light than lighter colors

darker absorb more light

8

which color is known to be the most pleasing and restful to the eyes

green

9

if a light source of 30 foot candles is directed a gray wall, 60% of the light will be reflect (40% absorbed) therefore ______ foot lamberts is reflected and ____ foot candles is absorbed

18 foot lamberts reflected
12 foot candles absorbed

10

approximately what percent of light is reflected off the following colors

white
pink, yellow, light blue
medium blue
red

white 90%
pink, yellow, light blue 65%
medium blue 35%
red 15%

11

a good contrast is considered between __- an d___ percent

60 and 80%

12

what is the formula for contrast and what would be the contrast between a yellow background and a medium blue object

yellow - 65%, medium blue 36%

background reflection - object reflection
65-36=29

29/ background contrast x 100
29/65 x 100 = 44.6 % contrast

13

visibility depends on the ______ between an object and background

contrast

14

what are the two types of glare

direct glare from a bright light source

reflected glare caused by specular reflection (reflection off a shiny surface)

15

what is an example of specular reflection

the sun reflecting off the ocean water

16

the best lighting for studying is a combination of ______ and _______ lighting

direct and indirect lighting

17

what type of light produces soft shadows

diffused light (light reflected off walls or floors)

18

what type of light produces sharp, dense, direct shadows

direct lighting

19

what is an e.g. of highly diffused light and what is it useful for

an overcast or cloudy day, little or no shadows are produced

great for photography

20

what three factors are needed for proper lighting

illumination (foot candles)
brightness (food lamberts)
contrast

21

the intensity of illumination on a surface varies _______ as the square of its distance from the light source

it varies inversely

22

what is the recommended foot candles for a normal classroom

50

23

does poor lighting cause eye damage?

no, just fatigue and stress

24

is fluorescent lighting more or less efficient than incandescent lighting

more efficient

25

a 40 watt fluorescent light produces nearly ____ more times light than a 60 watt tungsten light bulb

4 times more

26

how does a fluorescent bulb work

electrical current goes through mercury vapor creating an arc that produces uv light. the uv light excites the fluorescent chemicals which coat the inside of the bulb.

27

the buzzing noise commonly heard from fluorescent lighting is from the ______

transformer or ballast

28

the transformer or ballast converts _____ into _____

house hold light into a high voltage

29

what are disadvantages to fluorescent lighting

produces a cooler light which makes skin look pale and pictures look green

30

fluorescent lighting forms ________ in the air. is this beneficial or negative?

negative ions

beneficial, good for human body, makes air smell clean and help pollutants fall out of the air

31

what is infrared light

the lower wavelength light spectrum.

32

what are some uses of IR light

to keep food hot
chemical spectroscopy
enamel drying
dehydrating textiles or paper

33

what are the negative effects of IR light

may cause eye injury (produces cataracts)
can burn skin

34

what is UV light

the high wavelengths of light

35

what can UV light be used for

as a disinfectant

36

what does LASER stand for

light amplification stimulated emission radiation

37

what is LASER

a high intensity light at a single wavelength

38

how can a laser be dangerous

direct exposure to the eye can cause blindness