2 Spectrum of Light2 7 Mixing Colors by Addition7 2222 Mixing Colors by Subtraction – Define 2727 Colored Filters 4545 Primary Colors from C, M, Y 4848

2 Spectrum of Light 7 Mixing Colors by Addition22 Mixing Colors by Subtraction – Define27 Colored Filters45 Primary Colors from C, M, Y48 Color Printing51 Mixing Paints56 Physicists vs Artists60 Illuminating Using Colored Light

Investigating Color

CreatedBy

Dick Heckathorn1 April 2K+2

I. The Spectrum of Light

A. White light can be separated into different colored lights called the spectrum.

1. Inv: How Can A Prism Be Used to Separate White Light Into Its Component Colors?

a. Look through a prism.

b. Shine ray of light into prism

c. Rotate prism as light passes through.



2. Demo-Disc: What Does the Prism Do to the Light?

a. Shine light from aluminum slide through a prism.

b. Block out all but red light.

c. Add second prism.

d. Mount second prism behind first.



3. How Does a Diffraction Grating Be Used to Separate White Light Into Its Component Colors?

a. Look through a grating at showcase bulb



3. How Does a Diffraction Grating Be Used to Separate White Light Into Its Component Colors?

b. Look at spectrum using cardboard with slit on overhead and with grating fastened to overhead lens.

II. Mixing Colors By Addition

A. Different colored lights overlapping on a white surface are perceived by the eye-brain system as the additive combination of the individual colors.

1. What Happens When Colors of Light Are Mixed?

a. Have students perform color addition using ray boxes.




b. Overlap colors using projector and 3 mirrors




c. Mount color wheel on wall.



1. What Happens When Primary Colors Of Light Are Mixed?

R + G ____

R + B ____

G + B ____

Yellow

Magenta

Cyan



1. What Happens When Opposite Colors Of Light Are Mixed?

B + Y ____

R + C ____

G + M ____

White

White

White



1. What Happens When Opposite Colors Of Light Are Mixed?

When two colors are added together that produces white light, we call them complementary colors.



2. What Are Colored Shadows?

a. Look at shadow produced using light from overhead or projector.




b. Look at shadow produced using two light bulbs separated by some distance.




c. Look at shadows produced using red, green and blue bulbs individually and in combinations of first 2 and then all three.




d. Quiz


B. Very small and closely spaced areas of color are perceived by the eye-brain system as the additive combination of the individual colors.

1. What Do Colors On A Color TV Screen Look Like Up Close?

a. Freeze a colored video on a TV screen.

b. Investigate using a lens.



1. What Do Colors Of A Comic Strip Look Like Up Close?

a. Investigate using a magnifying lens.



1. What Do Colors Of Colored Objects In Your Text Look Like?

b. Investigate using a magnifying lens.



1. What Do Black And White Pictures In A Newspaper Look Like?

c. Investigate using a magnifying lens.

III. Mixing Colors By Subtraction

A. Colored lights and colored objects can be described in terms of three attributes: hue, saturation and brightness. 1. The Attributes of Color

a. Hue – Main Color NameA sensation

b. Saturation – Purity of ColorRich or pale – Strong or weak

c. Brightness – IntensityA sensation


A. Colored lights and colored objects can be described in terms of three attributes: hue, saturation and brightness. 1. Naming Colored Lights and Colored

Objects. a. What we perceive when:

• looking at the source or • an object illuminated by a

source• the object is illuminated with

white light


A. Colored lights and colored objects can be described in terms of three attributes: hue, saturation and brightness. 1. Naming Colored Lights and Colored

Objects. a. What we perceive when:

• the object is illuminated with any color of light.

Say the Color, not the Word

YELLOW BLUE ORANGE

BLACK RED GREEN

PURPLE YELLOW RED

ORANGE GREEN BLACK

BLUE RED PURPLE

GREEN BLUE ORANGE

Say the Color, not the Word

YELLOW BLUE ORANGE

BLACK RED GREEN

PURPLE YELLOW RED

ORANGE GREEN BLACK

BLUE RED PURPLE

GREEN BLUE ORANGE

Say the Color, not the WordYELLOW BLUE ORANGE

BLACK RED GREEN

PURPLE YELLOW RED

ORANGE GREEN BLACK

BLUE RED PURPLE

GREEN BLUE ORANGE

Left – Right Conflict within brainYour right brain tries to say the color but your left brain insists on reading the word.


B. A colored filter has the property of transmitting certain colors and absorbing others. The name of the filter is determined by the color of light transmitted when white light is incident on the filter.


B. A colored filter has the property of transmitting certain colors and absorbing others.1. What Do Colored Filters Do?

a. Look through one colored filter at a time while looking at white light.



Using:• cardboard with slit on projector• grating over projection lens• colored filters

Examine what R, G, B, filters do.



a. Look through red

White R + G + BRed - G -

B



b. Look through green

White R + G + BGreen -R - B



c. Look through blue

White R + G + BBlue -R - G



d. Look through red and green

Red - G - BGreen - B - R Black



e. Look through red and blue

Red - G - BBlue - G - R Black



g. Look through green and blue

Green - B - RBlue - G - R Black



Using cardboard with slit on projectorgrating over projection lenscolored filters

Examine what C, M, Y, filters do.



a. Look through Cyan

White R + G + BCyan - R



b. Look through Magenta

White R + G + BMagenta - G



c. Look through Yellow

White R + G + BYellow - B



d. Look through yellow and magenta

Yellow - BMagenta - GRed



e. Look through yellow and cyan

Yellow - BCyan - RGreen



f. Look through magenta and cyan.

Magenta - GCyan - RBlue


B. A colored filter has the property of absorbing certain colors and transmitting others. 1. What Do Colored Filters Do?

g. Summarya. Yellow and Magentab. Yellow and Cyanc. Cyan and Magenta

RedGreen

Blue

Look at Color Power Point


C. The primary colors for mixing by subtraction are cyan, magenta and yellow.

1. Diagram For Overlapping Filters

Yellow Cyan

White - B Yellow - R = Green

(R+G+B) - B (R +G) - R = G



1. Diagram For Overlapping Filters.

Yellow Magenta

White - B Yellow - G = Red

(R+G+B) - B (R +G) - G = R



1. Diagrams For Overlapping Filters.

Magenta Cyan

White - G Magenta - R = Blue

(R+G+B) - G (R + B) - R = B


D. The primary colors used in the printing process are: cyan, magenta and yellow.

1. How is a colored picture made?

a. Color Poster

b. Show Picture of Garfield


E. The mixing of colored paints involves both additive and subtractive processes.

Predicting the resulting color is complicated because it depends on the physical properties of paints.



1. The Mixing of Paints and the Artist's Primary Colors

The mixing of water colors and printers inks are similar to

“mixing” color filters.




Mixing pigment-based paints are not so simple.




Paint consists of tiny solid particles in a transparent medium.

The particles have no color or are clear with dye added




Final result affected by

Density of ParticlesProperties of transparent

mediumSupport on which the paint is laid


F. The naming of the primary colors by physicists and artists differ.

The physicists primary colors of lightRed – Green – Blue

The physicists secondary colors of lightMagenta – Cyan – Yellow

The artist’s primary colors of pigmentsRed – Turquoise - Yellow



The physicists secondary colors of light Magenta – Cyan – Yellow The artist’s primary colors of pigments

Red – Blue – Yellow

Thus to a physicistArtists say Red - Physicists call magenta

Artists say Blue - Physicists call cyan



The physicists secondary colors of light Magenta – Cyan – Yellow The artist’s primary colors of pigments

Red – Blue – Yellow

Baggie Ad: Blue - Yellow Green Physicist: Cyan - Yellow Green

IV. What is the Color?

IV. The color an object appears depends on the color of the illuminating light and the properties of the object.

1. What Is The Color of That Object?

a. Shine colored light on colored cardboard.



1. What Is The Color of Red, Green, Blue on monitor or computer screen?

d. Use “red”, “green”, “blue” filter to view the screen.

Why do they appear as they do?

RedGreenBlue



c. Results seen with eye.

red green blue

red red red black red black

green blackgreen green green black

blue black blue black blue blue



1. What Is The Color of Red, Green, Blue using Felt Tip Markers?

b. Shine white light on the colors.

Why do they appear as they do?



e. Results viewing with filter?

red green blue

red red red black red black

green blackgreen green green black

blue black blue black blue blue

1. What are the colors of the letters?

V. Evaluation

2. Are you color blind?

1. Is it a green filter?

V. Things for Thought

2. What color is the baggie strips?

3. What color is the printing on

plastic?

That’s all folks!

Documents

2 Spectrum of Light2 7 Mixing Colors by Addition7 2222 Mixing Colors by Subtraction – Define 2727 Colored Filters 4545 Primary Colors from C, M, Y 4848