1. Light and Color

2. An objects color depends on the wavelength of light it reflects and that our eyes detect. White light is a blend of all colors. When we see a red object, it is because more red wavelengths are being reflected. The other color wavelengths are being absorbed.

3. Black and White Black is not a color. Objects that appear black are absorbing all wavelengths of color. White objects appear white because they are reflecting all colors of visible light.

4. Light and the eye Light enters the eye through a lens and focuses on the retina (the movie screen of the eye) at the back of the eye. Two types of light absorbing cells are found on the retina. Cones and Rods Cones allow you to see color and detailed shapes of objects. Good for daytime vision. Rods are sensitive to dim light and are good for night vision.

5. Rods and Cones (Cont.) There are 3 types of cones. Red cones respond to reds and yellows Green cones respond mostly to yellows and greens. Blue cones respond mostly to blue and violet. When your eye sees yellow (like seeing a banana) the red and green cones respond. When your eyes see a mixture of red light and green light the same red and green cones respond. Your brain doesn’t know the difference between incoming yellow light and red light mixed with green light.

6. Diagram of the Eye Create an eye diagram with labels. Side view Include Lens, Retina, Rods, Cones and Optical Nerve.

7. Color Blindness Color blindness is caused by malfunctioning cones. 8% of men and.5% of women experience color blindness. Traffic lights must be read by position not color for these people.

8. Filtering Colors A filter is a transparent material that selectively transmits light. Blue filters allow blue light to transmit. All other colors are absorbed.

9. Mixing Colors All visible light colors can be made by mixing 3 colors. Red, green and blue. These are the primary colors of light These colors correspond to the 3 types of cones in the retina.

10. Mixing Colors Mixed together in equal amounts, they create white light. (Middle)

11. Mixing Paint If you mixed equal amounts of red, green and blue paint, you would not get white paint. Paint gets its color from mixtures of pigments. The color of pigments results from the different wavelengths of light that the pigment reflects. Pigments are made of chemical compounds like titanium oxide which is a bright white pigment reflecting all colors.

12. Mixing Pigments You can make any pigment color by mixing different amounts of the three primary pigments – magenta (bluish red), cyan (greenish blue), and yellow.

13. Mixing Pigments Continued Different pigment mixtures reflect a range of colors. Yellow, viewed in white light, is actually reflecting yellow, red, orange and green light and absorbing blue and violet light.

14. Why Black in the Center? The overlapping center appears black because the 3 blended primary pigments absorb all the primary colors of light.

15. Primary Colors of Light vs Primary Pigments Recall that when the 3 primary colors of light overlap they create a white light. They are called additive colors. When the primary pigment colors combine to create black they are called subtractive colors.