2. Light Polarization

3. These three are the same… Light *pure energy Electromagnetic Waves *energy-carrying waves emitted by vibrating electrons Photons *particles of light

6. Polarization Light: Waves in only one direction Not polarized light: waves in random scatter

7. Blue sky has some glare or polarization

9. How do we make Polarized Light?

10. Light Polarization Parallel, crossed, 45 degrees (100%, 0%, 70%) Each Polaroid pick only 1 direction of light

11. What is crossed? Two polaroid filters at 90 degrees to another No light gets through First vertical filter blocks horizontally polarized light Second horizontal filter blocks remaining vertical light

12. How do we make Polarized Light? I. Polarizers- Polarizers are made of long chained molecules which absorb light with electric fields perpendicular to the axis.

13. How do we make Polarized Light? II. Reflections off non-metals

14. How do we make Polarized Light? III. Refraction- -light bending -some calcite minerals

15. How do we make Polarized Light? II. Reflections off non-metals

16. What happened to that blue sky?

17. Less and less b lue

18. No blue left if look long ways across sky like at sunrise and sunset

19. Space=dark=no air to scatter light

20. Polarized sunglasses Most road glare is horizontally polarized

21. Polarized 3-d glasses (weaker effect if use different colors/prisms)

22. Check your understanding Suppose that light passes through two Polaroid filters whose polarization axes are parallel to each other. How does the final light compare to the original? A. 100% of original B. ½ light C. ¼ light D. no light

23. Check your understanding Light becomes partially polarized as it reflects off nonmetallic surfaces such as glass, water, or a road surface. The polarized light consists of waves vibrating in a plane that is ____________ (parallel, perpendicular) to the reflecting surface. A. Parallel b. perpendicular

24. Check your understanding Which sunglasses work best for glare A. both vertically polarized b. both horizontally polarized C. one side of each D. dark shades unpolarized

25. Demos: projector light corn syrup plastic ruler scotch tape polaroid films cell phone display glare on windows/clock computer screen