1. Light

2. Visible Light
Visible Light - the range of frequencies of electromagnetic waves that stimulates the retina of the eye

4. Visible Light The lowest frequency of light we can see is red light
The highest frequency of light we can see is violet light
EM waves with frequencies lower than red light are called infrared
EM waves with frequencies higher than violet light are called ultraviolet

5. Sources of Light Sources of Light
Luminous source: emits light waves (Sun, light bulb)
Illuminated source: reflects light waves
(Moon)

6. What happens to the light?
When light waves strike an object, the waves can be:
Absorbed by the object
Reflected by the object
Transmitted by the object

7. Light and Matter

8. Transparent Materials that transmit light waves Examples: air glass
some plastics

9. Translucent
Transmit light but do not permit objects to be seen clearly
Examples:
lamp shades
frosted glass

10. Opaque
Transmit no light
Absorb or reflect all light waves

13. COLOR
Color
Newton determined that white light was made from a combination of color

14. Additive Color Mixing
White light = RED LIGHT + GREEN LIGHT + BLUE LIGHT
These are considered Primary Light Colors

15. Adding colors
White light can be split up to make separate colors. These colors can be added together again.
Adding blue and red makes magenta (purple)
Adding blue and green makes cyan (light blue)
Adding red and green makes yellow
Adding all three makes white again

17. Secondary Light Colors
Formed by mixing primary colors
Yellow
Magenta
Cyan

18. Complementary Colors Two colors that add to produce white light
Cyan and Red
Magenta and green
Yellow and blue

19. For more practice with mixing colors of light:

20. Seeing color
The color an object appears depends on the colors of light it reflects.
For example, a red book only reflects red light:
Homework
White
light
Only red light is reflected

21. A white hat would reflect all seven colors:
A pair of purple pants would reflect purple light (and red and blue, as purple is made up of red and blue):
Purple light
A white hat would reflect all seven colors:
White
light

22. Filters A filter can be used to block certain colors of light
Filters allow only certain frequencies to be transmitted.
For additional help with filters go to:

23. Using filters
Filters can be used to “block” out different colors of light:
Red Filter
Magenta Filter

24.
A cyan filter absorbs red light, the magenta filter absorbs green light, and the yellow filter absorbs blue light.

25. Making Color by Subtraction
Objects can reflect and transmit light, and they can also filter light.
Colored filters transmit certain frequencies of visible light while absorbing others.
A blue filter absorbs red and green, a red filter absorbs green and blue, and the green filter absorbs red and blue.

26. Primary Pigment
Pigments are like dyes except they are made of minerals.
Primary pigments absorb only one primary color of light. This means they reflect 2 colors of light.
The primary colors of pigments are yellow, cyan and magenta.
A color printer uses the primary colors of paint to produce any color imaginable.

27. Secondary Pigments
A pigment that absorbs two colors of light and reflects one is a secondary pigment.
The secondary pigments are red, blue, and green.
The primary pigment colors are the secondary light colors and the secondary pigment colors are the primary light colors.

28. Complementary Pigments
Red pigment is complementary to cyan.
Blue pigment is complementary to yellow.
Green pigment is complementary to magenta.
Complementary pigments are those that when mixed, result in a black color.

29. Color Blindness

30. Using colored light
If we look at a colored object in colored light we see something different. For example, consider the following:
Shirt looks red
White
light
Shorts look blue

31. In different colors of light these clothes would look different:
Shirt looks red
Red
light
Shorts look black
Shirt looks black
Blue
light
Shorts look blue