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Inv est iga tin g Co lor In the Classroom

This resource explores the spectrum of light, mixing colors by addition and subtraction, colored filters, primary colors, color printing, mixing paints, and the intersection of physics and art.

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Inv est iga tin g Co lor In the Classroom

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  1. InvestigatingColorIntheClassroom Created for CVCA Physic By Dick Heckathorn 2June 2K+4

  2. 2 Spectrum of Light 7 Mixing Colors by Addition 22 Mixing Colors by Subtraction – Define 27 Colored Filters 45 Primary Colors from C, M, Y 48 Color Printing 51 Mixing Paints 56 Physicists vs Artists 60 Illuminating Using Colored Light

  3. 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? • Look through a prism. • Shine ray of light into prism • Rotate prism as light passes through.

  4. I. The Spectrum of Light • 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.

  5. I. The Spectrum of Light • How does a diffraction grating be used to separate white light into its component colors? • Look through a grating at a showcase bulb. • b. Look at spectrum using cardboard with slit on overhead and with grating fastened to overhead lens.

  6. II. Mixing Colors By Addition • 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. Use ray box to observe the overlapping of light from red,green and blue filters.

  7. II. Mixing Colors By Addition • b. Demonstrate: Overlap colors using projector and 3 mirrors • c. Mount color wheel on wall.

  8. II. Mixing Colors By Addition • 2. What happens when primary colors of light are overlapped? R + G ? Yellow R + B ? Magenta G + B ? Cyan

  9. II. Mixing Colors By Addition • 3. What happens when opposite colors of light are overlapped? B + Y  ? White R + C ? White G + M ? White When two colors are added together that produces white light, we call them complementary colors.

  10. II. Mixing Colors By Addition • B. What Are Colored Shadows? • a. Look at shadows produced using red,green and blue filters with ray box first individually and then in combinations of first 2 and then 3. • b. Look at shadow produced using light from overhead or projector. • c. Look at shadow produced using two light bulbs separated by some distance.

  11. II. Mixing Colors By Addition • d. Demonstrate shadows using red,green and blue bulbs individually and then in combinations of first 2 and then all three. • e. Quiz

  12. II. Mixing Colors By Addition • C. 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 Colors Make up a TV Screen? a. Freeze a colored video or • b. Tape of color bars from TV • Investigate using a lens.

  13. II. Mixing Colors By Addition • Use a lens to view a comic strip up close? • Use a lens to view colored objects close up. (page 426 of text) • 4. Use a lens to view black and white pictures in a text and/or a newspaper.

  14. B B Y Y + + B -Y -B Y White White

  15. II. Mixing _______ By Addition • Different small images on a piece of paper, TV screen etc. when perceived by the eye-brain can provide very interesting results. • 1. What happens when many small images are used to make a picture? • 2. Does the image change when viewed from different distances? Try it.

  16. Say the Color, not the Word YELLOW BLUE ORANGE BLACK RED GREEN PURPLE YELLOW RED ORANGE GREEN BLACK PURPLE BLUE RED GREEN BLUE ORANGE

  17. Say the Color, not the Word • YELLOWBLUE ORANGE • BLACK RED GREEN • PURPLEYELLOWRED • ORANGEGREENBLACK • BLUE RED PURPLE • GREEN BLUEORANGE Left – Right conflict within brain Your right brain tries to say the color but your left brain insists on reading the word.

  18. III. Mixing Colors By Subtraction • Colored lights and colored objects can be described in terms of three attributes: hue, saturation and brightness. • The Attributes of Color • a. Hue – Main Color Name • A sensation • Saturation – Purity of Color • Rich or pale – Strong or weak • Brightness – Intensity • A sensation

  19. III. Mixing Colors By Subtraction • 2. The color of a light source is described using the light that enters ones eyes. • 3. The name of a filter is determined by the color of light transmitted when white light is incident on the filter.

  20. III. Mixing Colors By Subtraction • Look throughred • whiteR+G+B • red-G-B • b. Look throughgreen • whiteR+G+B • green-R-B • c. Look throughblue • whiteR+G+B • blue-R-G

  21. III. Mixing Colors By Subtraction • d.Look throughredandgreen • whiteR+G+B • red-G-B • green-R-B • color seenBlack • Look throughredandblue • whiteR+G+B • red-G-B • blue-R-G • color seenBlack

  22. III. Mixing Colors By Subtraction • f. Look throughgreenandblue • whiteR+G+B • green-R-B • blue-R-G • color seenBlack When we say we see black what do we mean? The black sensation is the result of no color reaching our eyes.

  23. III. Mixing Colors By Subtraction • Look throughcyan • whiteR+G+B • cyan-R • b.Look throughmagenta • whiteR+G+B • magenta-G • c.Look through yellow • whiteR+G+B • yellow  -B

  24. III. Mixing Colors By Subtraction • d. Look through yellow andmagenta • whiteR+G+B • yellow  -B • magenta-G • color seen: R • Look through yellow and cyan • whiteR + G + B • yellow  -B • cyan-R • color seen: G

  25. III. Mixing Colors By Subtraction • f. Look throughmagentaandcyan. • whiteR+G+B • magenta-G • cyan-R • color seen:B • g. Summary • yellow andmagenta • yellow andcyan • cyanandmagenta Red Green Blue

  26. III. Mixing Colors By Subtraction • 2. Demonstrate what light red,green,blue, cyan,magenta and yellow filters. • transmit using: • - overhead projector • - cardboard with slit on projector • - grating over transmitted light • - colored filters in 2 x 4 cards

  27. Go to • Color • Explanation Click Now

  28. III. Mixing Colors By Subtraction • The primary colors for printing and painting subtraction arecyan,magentaand yellow. • Diagram for overlapping filters • yellow cyan • white •  • -B •  • yellow • -R • = • green (R+G+B)  -B  (R +G) • -R • = • G

  29. III. Mixing Colors By Subtraction • yellow magenta • white •  • -B •  • yellow • -G • = • red (R+G+B)  -B  (R +G) • -G • = • R • magentacyan • white •  • -G •  • magenta • - R • = • blue (R+G+B)  -G  (R + B) • - R • = • B

  30. III. Mixing Colors By Subtraction • 1. How is a colored pictures made? • a. Three and Four Color Printing • b. Rifle Picture • c. Picture of Garfield

  31. III. Mixing Colors By Subtraction • D. 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.

  32. III. Mixing Colors By Subtraction • The mixing of water colors and printer inks are similar to “mixing” color filters. • Mixing pigment-based paints are not so simple.

  33. III. Mixing Colors By Subtraction • 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 • Properties of transparent medium • Density of the particles • Material on which the paint is applied

  34. III. Mixing Colors By Subtraction • E. The naming of the primary colors by physicists and artists differ. • The physicists primary colors of light are: • redgreenblue • The physicists secondary colors of light are: • magentacyanyellow • The artist’s calls its primary colors: • redblueyellow

  35. III. Mixing Colors By Subtraction • IN PHYSICS • The physicists secondary colors of light are • magentacyanyellow • The artist’s call their primary colors • redblueyellow • Conclusion: • Artists say red Physicists think magenta • Artists say blue Physicists think cyan

  36. III. Mixing Colors By Subtraction • Demonstrate • Baggie Ad: Blue - Yellow  Green • Physicist: Cyan - Yellow  Green

  37. What is the Color? • A. 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 red, green, and blue on the following slide? • a. Use red, then green, and finally a blue filter to view the slide. • What is observed?

  38. Red Green Blue

  39. Red Results seen with eye. red filter red green filter  black blue filter  black

  40. Green Results seen with eye. red filter black green filter  green blue filter  black

  41. Blue Results seen with eye. red filter black green filter  black blue filter  blue

  42. Red Green Blue

  43. What is the Color? • 2. What is the color of the letters made with colored magic markers? • a. Examine the letters looking first through a redfilter, then a greenfilter, and finally a bluefilter. • Describe what you see?

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