1. Light, Color, and Polarization
Unit 13: Light and Optics
Light, Color, and Polarization

2. Color Intro What are the primary colors of light?
List the colors of the rainbow in order
What do all the colors of the rainbow add up to?

3. Section 3: Visible Light and Colors
Characteristics
“White” light is a combination of red, orange, yellow, green, cyan, blue, and violet
A prism can separate these colors out
By refraction of different wavelengths of color

4. Visible Light 700 nm 400 nm Red orange yellow green cyan blue violet
Longest Wavelength
Lowest Frequency
Least Energy
Violet:
Shortest Wavelength
Highest Frequency
Most Energy

5. Primary Colors
Red
Blue
Green
Blue
Red
Green

6. Secondary Colors: Mixture of 2 Primary Colors
Magenta (Blue and Red)
Cyan (Blue and Green)
Yellow (Red and Green)
A mixture of all three primary colors produces white light
Blue
Red
Magenta
Blue
Blue
Green
Cyan
Blue
Red
Red
Yellow
White
Green
Green

7. Blue Red Green Since secondary colors are a mix of two primaries:
Mixing primary and secondary colors produces white light
White Light = Primary Color + Secondary Color
White Light = Blue + Yellow
White Light = Green + Magenta
White Light = Red + Cyan
Blue
Red
Green

8. Primary colors of light
Primary pigments (ink)
Red
Blue
Green
Magenta
Cyan
Yellow

9. Primary pigments (ink) adds up to black
Primary colors (light)
Red
Blue
Green
Primary pigments (ink)
Magenta
Yellow
Cyan
are secondary pigments
Primary colors add
up to white light
Red
Magenta
Yellow
Blue
Green
Cyan
are secondary colors
Primary pigments (ink) adds up to black
Yellow
Green
Red
Cyan
Blue
Magenta

10. Intro Index of Refraction
The principles of Refraction, Reflection, Diffraction are similarly applied to sound and light waves.
Review:
Reflection: light bounces off reflective surfaces
Ex: looking a mirror or reflection in water
Diffraction: bend of light around a barrier
Ex: a dim corner of a dark room when light comes through an open door
Refraction: light bends as passes from one media to another. Is determined by Snell’s Law
Ex straw looks like it is bent in a glass of water

11. Rainbows are produced by the refraction of light

12. Thin Films
Light from one side of a bubble cancels out light from the other side showing color from white light

13. Diffraction and Refraction and not the same!
Diffraction Grating can be used to disperse light into colors like a prism
A prism used refraction to disperse light
Diffraction gradients use the interference of light to produce colors

14. Diffraction and Polarization Clip

15. Polarization of Light Light is an electromagnetic wave
These waves produce an electric field at a right angle to the magnetic field
Usually the rays are unpolarized which means they are oscillating in random directions.

16. Polarized Light
Some crystals can cause unpolarized light to pass through and produce polarized light which has its electromagnetic fields aligned in the same direction.
Transmission axis- line along which light is polarized

17. Transmission axis- line along which light is polarized
Light at 90º to the transmission axis cannot pass through.

18. How polarized sunglasses work
Glare
When light reflects off the ground (a horizontal surface) it is polarized horizontally.
Sunglasses stop glare
They are polarized vertically so that horizontal glare cannot get through