1. Announcements 10/26/11 Prayer Slinkies: Please turn-in, and cross your name off of the sign out list. Exam 2 starts tomorrow, goes through Tuesday evening a. a.Covers through tonight’s HW (HW 24) b. b.Like last time, no notes allowed, but I give you equations Comment from Chris: when turning in multiple assignments, staple them separately. Found a white sweater after review session last night. Overboard

2. Reading Quiz Which of the following scientists did not attempt to make a measurement of the speed of light? a. a.Einstein b. b.Fizeau c. c.Galileo d. d.Roemer e. e.Michelson (OK, this is not the answer, but I felt his name should be included on the list even though he wasn’t mentioned in today’s reading, because he performed the “canonical experiment”) Advertisement for Phys 471 How did they all attempt to measure it?

3. xkcd Advertisement for Phys 222

4. The wave nature of light What is “waving”? http://stokes.byu.edu/emwave_flash.html Medium? Polarization: quick definition

5. Reading Quiz A beam of light passes through a hole of diameter d in a metal plate. Under what condition are we allowed to ignore the diffraction or “spreading” of the light? (This is called the ray approximation.) a. a.When λ << d b. b.When λ ≈ d c. c.When λ >> d

6. Next three slides: image credit to Dr. Durfee

9. Index of Refraction Book table v = c/n

10. Index of Refraction Song: Roy G. Biv (start at 0:30) http://www.youtube.com/watch?v=Gf33ueRXMzQ Image: http://en.wikipedia.org/wiki /Dispersion_(optics) http://en.wikipedia.org/wiki /Dispersion_(optics) red Different wavelengths have different speeds! Different wave- lengths (k values) have different speeds! v = f Dispersion! green blue ( going into material) inside = vacuum /n

11. Thought question Which color of light travels fastest in glass? a. a.Red b. b.Green c. c.Blue d. d.Same

12. Absorption “Lorentz oscillator model” From Peatross & Ware, textbook for Phys 471 absorption index of refraction increasing frequency (decreasing ) “anomalous” index of refraction Why is blue light slower through glass than red light?  It’s closer to an absorption region

13. Index of Refraction Light ray at boundary 11 22 fast light (smaller n) slow light (larger n)

14. Snell’s Law n 1 sin  1 = n 2 sin  2 11 22 fast light (smaller n) slow light (larger n) Advertisement for Phys 442/471

15. Law of Reflection  refl. =  1 11 22 fast light (smaller n) slow light (larger n)  refl. Reflections occur off of any boundary, not just “mirrors” When will you have no reflection?

16. Fresnel Coefficients / Fresnel Equations If near perpendicular (1-D problem) For arbitrary angle (these eqns not needed for HW/exam) Advertisement for Phys 442, Phys 471 Look familiar??

17. Thought question I send white light into a prism as shown below (n>1). Will the red part of the “rainbow” be on the top or the bottom of the outgoing fan of light? a. a.top b. b.bottom top bottom

18. Demos Reflection/refraction using water-soluble oil “Blackboard optics”