Light & Color Ch 22.4 8th
Transcript of Light & Color Ch 22.4 8th
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Chapter 22 Section 4
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Name and describe the 3 ways light interactswith matter
Explain how the color of an object isdetermined
Explain why mixing colors of light is calledcolor addition
Describe why mixing colors of pigments iscalled color subtraction
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Light interacts with matter in 3 ways:Reflection
Absorption
Transmission
It is reflected if it is bounced off an object
Absorption is the transfer of light energy to
matterTransmission is the passing of light through
matter
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Transparent: matter through which light iseasily transmittedAir, glass, water, plastic wrap
Translucent: transmits light but also scattersthe light as it passes through the matterFrosted glass, wax paper
Opaque: matter that does not transmit lightMetal, wood, aluminum foil
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Humans see different wavelengths of light as differentcolors
Long wavelengths are seen as red
Short wavelengths are seen as violet
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White light strikes a colored object, somecolors are absorbed, some are reflected
The colors of light that are reflected by anopaque object determine the color you see
White objects appear white because all the
colors of light are reflected
Black is the absence of color (all colors areabsorbed)
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Ordinary window glass is colorless in whitelight because it transmits all the colors thatstrike it
But, some transparent objects are colored
You see the color light that is transmitted,
the other colors are absorbed
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Primary colors of light:Red
Green
Blue
These colors can be combined in differentratios to produce many colors
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When colors combine, you see differentcolors
Combining of colors: Color addition
When 2 primary colors of light are addedtogether, you see a secondary color of light
Cyan (blue+green)Magenta (blue+ red)
Yellow (red + green)
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http://www.daviddarling.info/images/color_1.jpg
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Colors on a color television are produced bycolor addition of the primary colors of light
TV screen are made up of tiny dots ofred,green, and blue
Each dot glows when it is hit by an electron
beam
Color addition produces the colors seen onthe screen
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Mixing colors vs. mixing paint
Mixing red, blue, and green paint does not
produce white paint
Paint contains pigments
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Pigment: a material that gives a substance itscolor by absorbing some colors of light andreflecting others
Chlorophyll and melanin are 2 examples ofpigments
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Each pigment absorbs at least one color of light
Primary pigments are yellow, cyan, magenta
When you mix pigment together, more colors of light areabsorbed or taken away: color subtraction
http://www.ux1.eiu.edu/~cfadd/3050/Ch17Color/17Images/image43.gif