1. Chapter 25 Reflection and Refraction

3. Reflection

4. We will focus on specular reflection

5. The Law of Reflection normal normal All angles are measured with respect to the normal.

6. Multiple reflections

7. Snell’s Law of Refraction

8. Refractive Index

9. Useful facts

10. Reflection and refraction

11. Be careful with the normal

12. More on refractive index

13. Wavelength in different medium

14. Find the refractive index and the speed of light in the liquid

15. Solution

16. Different colors different speed

17. Dispersion

18. What happened to my ruler?

19. Explanation

20. Optical Illusion

21. The image

22. How to catch a bug

23. Find θ air for the following cases: θ water θ air 40° 47° 48° 48.75° 50° n water = 1.33

24. Solution θ water θ air 40°58.7° 47°76.6° 48°81.3° 48.75°89.4° 50°[Error]

25. Total Internal Reflection

26. A slightly more accurate picture

27. Total internal reflection (TIR) Total internal reflection occurs when θ incident > θ c. It is when all the refracted light disappear and all the light got reflected back.

28. The critical angle, θ c θ c is the angle of incidence θ incidence when θ refraction = 90 o

29. Wrong Answers! Define critical angle: XCritical angle is when TIR happens. (Is what???) XCritical angle is the angle of incidence when TIR happens. (TIR happens for many values of θ incidence ) XCritical angle is the angle when TIR begins. (Which angle???) Define TIR: XTIR is when the the angle of incidence = critical angle. (What about θ incidence >θ c ?) XTIR is when the the angle of incidence > critical angle. (Circular logic)

30. Find the critical angle for diamond in air

31. Shiny diamonds and total internal reflection

32. Cubic Zirconium Refractive index: 2.15 to 2.18 (diamond: 2.42) Hardness: 8.5 to 9 (diamond: 10) Ingredients: zirconium oxide, magnesium, calcium (diamond: carbon)

33. Applications of TIR Fiberoptics

34. Total internal reflection

35. Huygen’s Principle Every point of a wave front may be considered the source of secondary wavelets that spread out in all directions with a speed equal to the speed of wave. The final wave is the sum of all these secondary wavelets.

36. Deriving Snell’s Law of Refraction

37. Principle of Least Time Light always travels between two points in the path that takes the least amount of time.