Transcript Light & Color

Light & Color
Light:
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Light that can be sensed by our eyes is
Visible Light
Visible light consists of a continuous range
of wavelengths or frequencies
Specific wavelengths correspond to a
specific color based upon how we perceive
light of that wavelength
Dispersion & Recomposition:
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If a prism is placed in a beam of white light:
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Dispersion occurs resulting in the ‘separation’
of light into a spectrum of colors
A type of refraction
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Refractive index varies with the wavelength or
color of light
Dispersion due to different refractive angles
How rainbows occur
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Recomposition recombines the colors of
the spectrum
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When light strikes an object, the specific
wavelengths can be absorbed or reflected
The wavelengths that are reflected by an
object, cause the perceived color of the
object
ROYBIV all absorbed by object
G
Ex.
ROYGBIV
Capable of absorbing
ROYBIV
G reflected
Therefore object “appears”
green
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If all absorbed, then object appears black
If all reflected, then object appears white
What color will the objects appear to
be?
ROYGBIV
GBIV
Capable of
absorbing ROY
ROYGBIV
RO
Capable of
absorbing YGBIV
ROYGBIV
nothing
BLACK
Capable of absorbing
ROYGBIV
Viewing objects:
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Objects may be viewed through filters &/or
under different light
Causing the color of objects to be perceived
differently
Recall white light is ROYGBIV
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Filters will only allow specific colors of light
(& the color on either side in the spectrum)
to pass
Ex. R
O
Y
G
G
B
V
V
Blue Filter
B
White light passes through a yellow filter.
What color light will pass?
R
O
Y
G
B
V
O
Y
G
Yellow Filter
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Recall colors are perceived b/c of the color
of light reflected
Viewing objects under different color light
will affect the perceived color since some
colors may or may not be present to be
reflected!!!
A white dress is viewed under a blue filer.
What color will the dress appear?
R
O
Y
G
B
V
BLUE
G
B
Blue Filter
V
A yellow shirt is viewed under a green filer.
What color will the shirt appear?
R
O
Y
G
B
V
Yellow
Y
G
B
Green Filter
A red shirt is viewed under a yellow filer.
What color will the shirt appear?
R
O
Y
G
B
V
BLACK
O
Y
G
Yellow Filter
A blue shirt is viewed under red light. What
color will it appear?
R
O
Y
G
B
V
BLACK
A blue shirt is viewed under green light.
What color will it appear?
R
O
Y
G
B
V
BLUE
Standing on a stage, a singer is
illuminated by three lights, each
emitting a different color.
When the first light is used, he appears to be
wearing black shoes, red pants & a red shirt
When the second light is used, he appears to
be wearing blue shoes, black pants & a blue
shirt
When the third light is used, he appears to be
wearing black shoes, black pants & a green
shirt
What color are the singer’s shoes, pants & shirt?
Reflecting blue
so….
Reflecting red
so…
Reflecting all
so…
Shoes are blue
Pants are red
Shirt is white
Shoes
1st Light
Blk
Red
2nd Light
Blue
Blue
3rd Light
Green
Blk
----GBV
-----
Pants
Red
Blk
Blk
RO
---------
Shirt
Red
Blue
RO
GBV
Green
YGB
Color Addition:
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White light is ROYGBIV but…
White light can also be produced by adding
colors (or frequencies)
Any three colors of light which produce
white light when combined are primary
colors of light
RED, GREEN & BLUE
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By adding primary colors of light, other colors
can be produced
Ex.
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TVs, computers, stage lights
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Yellow
Red
Green
White
Magenta
Blue
Cyan
Yellow
Magenta
Cyan
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Any two colors of light which when mixed
together in equal intensities produce white
are complementary colors of eachother
Ex.
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Red & Cyan
Blue & Yellow
Green & Magenta
If magenta light and yellow light are added
together, will white light be produced?
Magenta = Red & Blue
Yellow = Red & Green
Light will appear “light pink”
Color Subtraction:
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Process of “removing” color
Increasing absorption of colors and decreasing
reflection of colors
Blue absorbed
Ex. R G B
RG
Red & Green Reflected
Therefore object “appears”
yellow
Pigment capable of absorbing
blue light
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Paint pigments, printer ink
What color would an object capable of absorbing
blue light appear?
Green absorbed
RGB
RB
Red & Blue Reflected
Therefore object “appears”
magenta
Pigment capable of absorbing
green light
Primary colors (pigments) of paint are cyan,
magenta & yellow
Blue
Cyan
Green
Yellow
Magenta
Red
Cyan absorbs Red
Magenta absorbs Green
Yellow absorbs Blue
Each primary color of paint absorbs one primary
color of light