1. Chapter 28: Color

2. The Color Spectrum Isaac Newton and his prism The spectrum (ROYGBIV) White light –Combination of all colors –Whit objects appear white –Colored objects appear their individual colors –Black is the absence of light

3. Black paper, carbon soot for example There is a little reflection off of black objects, otherwise you would not be able to see them

4. Color By Reflection Opaque materials-light passes back into he medium from which it came Color is due to how opaque objects reflect light Electrons vibrating at or below the material’s natural frequency will allow light to be reemitted Most materials absorb light of some frequencies and reflect the rest

5. Chlorophyll in a plant: absorbs most frequencies and reflects green Red rose: reflects red Objects can reflect only frequencies that are available in the area –Candlelight-deficient in high frequencies –Incandescent bulb-richer toward low frequencies –Fluorescent bulb: higher frequencies

6. Color By Transmission Red glass Blue glass Pigments in glass selectively absorb colored light Light of other frequencies is reemitted from atom to atom All visible frequencies is transmitted through clear glass Pixels in a computer and TV screen

7. When red light shines on a red rose, why do the leaves become warmer than the petals? When green light shines on a red rose, why do the petals look black?

8. Sunlight Brightness of solar frequencies is uneven Yellow-green is brightest part of sunlight Humans evolved in sunlight Fire trucks, airports, yellow sodium-vapor lamps, jogging vests, etc. Red and blue areas not as bright

9. Mixing Colored Light

10. Mixing Colored Light-Addition

11. Additive Process Mixing colored light is called color mixing by addition because when red, blue and green light are mixed, you get WHITE!

12. Complementary Colors Two colors of light that when mixed together make white! Yellow + Blue = White Magenta + Green = White Cyan + Red = White

13. Homework Answer Review Questions 1, 4, 6, 7 & 8 on page 439

14. Mixing Colored Pigments- Subtraction

15. Where is color mixing by subtraction (pigments) used? Ink Dyes Crayons Printing presses Make-up

16. Why is the sky blue? Why are sunsets red? Why are clouds white? Why is ocean water blue-green (cyan)?

18. Blue Sky Most UV absorbed by ozone layer Of visible frequencies, violet scattered the most, blue second most, red the least Eyes not very sensitive to violet, that’s why we see blue! Sky’s color/shade of blue varies based on the amount and number of particles present

19. Why are Sunsets Red?

20. Why are clouds white? Different-sized water droplets and ice crystals

21. Why is ocean water blue-green (cyan)? Blue and Green wavelengths are absorbed the least

22. The Atomic Color Code (Spectra)