Light & Color Ch 22.4 8th

8/9/2019 Light & Color Ch 22.4 8th

1/14

Chapter 22 Section 4


2/14

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


3/14

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


4/14

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


5/14

Humans see different wavelengths of light as differentcolors

Long wavelengths are seen as red

Short wavelengths are seen as violet


6/14

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)


7/14

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


8/14

Primary colors of light:Red

Green

Blue

These colors can be combined in differentratios to produce many colors


9/14

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)


10/14

http://www.daviddarling.info/images/color_1.jpg


11/14

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


12/14

Mixing colors vs. mixing paint

Mixing red, blue, and green paint does not

produce white paint

Paint contains pigments


13/14

Pigment: a material that gives a substance itscolor by absorbing some colors of light andreflecting others

Chlorophyll and melanin are 2 examples ofpigments


14/14

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

Documents

Light & Color Ch 22.4 8th