Prisms

1. Prisms, total internal reflection, polarization, how we see color, how vision is corrected and rainbows.

2. Prisms • High frequency light in a transparent medium travels slower than low frequency light (red light travels faster than violet light) • Thus, the different colors are refracted at different angles. • When white light is refracted twice, and the second surface is not parallel to the first, the dispersion is noticeable, thus the colors are observed. • If the two boundaries of the medium are parallel, the refractive effects at the first boundary are reversed at the second boundary.

3. Total Internal Reflection • Light can be reflected off a transparent medium boundary at a certain angle. • This angle is called the critical angle. Fiber Optics

4. Optical Fibers 29.12Total Internal Reflection Optical fibers, sometimes called light pipes, are transparent fibers that pipe light from one place to another. They do this by a series of total internal reflections. Optical fibers are useful for getting light to inaccessible places. Mechanics and machinists use them to look at the interiors of engines, and physicians use them to look inside a patient’s body.

5. Total Internal Reflection

6. Total Internal Reflection • http://www.phy.ntnu.edu.tw/java/optics/path_e.html • http://micro.magnet.fsu.edu/primer/java/refraction/criticalangle/index.html

7. Polarization of Light • Light consists of waves vibrating in all planes (360o). • A polarizer allows only the light wave along one plane to pass through. • Two polarizers if oriented at right angles will cancel all light. • Glare (reflected light polarized in a plane parallel to a non-metallic surface) is greatly reduced when using polarized lenses. • http://lectureonline.cl.msu.edu/~mmp/kap24/polarizers/Polarizer.htm

8. 28.1The Color Spectrum When sunlight passes through a prism, it separates into a spectrum of all the colors of the rainbow. roygbiv

9. dispersion • The phenomenon of incoming light of different wavelengths being bent at different angles when passing through a medium. • Red light is bent the least; violet the most • Prismatic effect (Dark Side of the Moon) produces rainbow colors: White light is separated into roygbv.

10. Isaac Newton—discovered that white light is composed of seven (or six) different colors of light Dispersion of white light into component colors Red Orange Yellow Green Blue Violet White Light A prism disperses white light into its primary frequencies of color

11. R Nave http://hyperphysics.phy-astr.gsu.edu/hbase/ems3.html

12. Prisms • http://www.physics.mun.ca/~jjerrett/dispersion/prism.html • http://micro.magnet.fsu.edu/primer/java/prism/index.html

13. Rainbows, etc. • http://mysite.verizon.net/vzeoacw1/rainbow.html • http://micro.magnet.fsu.edu/primer/java/refraction/refractionangles/index.html

14. Refraction • http://freespace.virgin.net/gareth.james/virtual/Optics/Refraction/refraction.html http://www.physicsclassroom.com/Class/refrn/u14l1f.html

15. http://acept.la.asu.edu/PiN/mod/light/opticsnature/pattLight4Obj1.htmlhttp://acept.la.asu.edu/PiN/mod/light/opticsnature/pattLight4Obj1.html • http://www.wrh.noaa.gov/Flagstaff/science/skyblue.htm • http://www.cordonline.net/laserapplets/

16. polarization • Light that is reflected or transmitted through specific materials such that all vibrations are oriented on single plane. • A polarizer allows only one plane of light through.

17. polarization 1st polarizer eliminates all but one plane 2nd polarizer when oriented at a right angle to this plane eliminates the remaining plane

18. polarization Sunlight is horizontally polarized when reflecting off a surface, producing glare (off a pond, river, car, road, etc.)