1. Physics 1051 Lecture 7 Slide 1 Refraction of Light –Part 2

2. Physics 1051 Lecture 7 Slide 2 Internal Reflection When light travels from a slow medium to a fast medium, the angle of refraction is larger than the angle of incidence. When the angle of refraction should be 90 o or greater, there is total internal reflection. The incident angle which predicts a 90 o refraction angle is called the critical angle. Applet

3. Physics 1051 Lecture 7 Slide 3 Critical Angle n 1 sin  c = n 2 sin 90 o n 1 sin  c = n 2 sin  c = n 2 / n 1  c = sin -1 (n 2 / n 1 ) For water:  c = 48 o The higher the index of refraction the lower  c

4. Physics 1051 Lecture 7 Slide 4 Fish Eye View

5. Physics 1051 Lecture 7 Slide 5 View of World Above Applet Applet

6. Physics 1051 Lecture 7 Slide 6 Bird & Fish

7. Physics 1051 Lecture 7 Slide 7 Internal Reflection All rays reflect internally, but the top three rays reflect only a small percentage internally; most energy leaves the prism. The fourth and fifth rays are reflected 100 % internally

8. Physics 1051 Lecture 7 Slide 8 Internal Reflection in Prisms

9. Physics 1051 Lecture 7 Slide 9 Internal Reflection in Diamond The critical angle for diamond in air is 24.5 o. Any ray which strikes the inside surface at an angle greater than 24.5 o will be totally internally reflected.

10. Physics 1051 Lecture 7 Slide 10 Fiber Optics

11. Physics 1051 Lecture 7 Slide 11 Fiber Optics

12. Physics 1051 Lecture 7 Slide 12 Dispersion Blue Bends Best

13. Physics 1051 Lecture 7 Slide 13 Different Frequencies Different Indices of Refraction

14. Physics 1051 Lecture 7 Slide 14 Refractive Index Function of Wavelength

15. Physics 1051 Lecture 7 Slide 15 Table of Indices

16. Physics 1051 Lecture 7 Slide 16 Refraction & Reflection in a Raindrop

17. Physics 1051 Lecture 7 Slide 17 Rainbow Formation An observer sees red light coming from droplets of water higher in the sky. Droplets of water lower in the sky send violet light to the eye.

18. Physics 1051 Lecture 7 Slide 18

19. Physics 1051 Lecture 7 Slide 19 Circular Rainbow

20. Physics 1051 Lecture 7 Slide 20 Double Rainbow Picture

21. Physics 1051 Lecture 7 Slide 21 Double Rainbow Picture

22. Physics 1051 Lecture 7 Slide 22 Rainbow Arch

23. Physics 1051 Lecture 7 Slide 23 Rainbow Zoom

24. Physics 1051 Lecture 7 Slide 24 Double Rainbow

25. Physics 1051 Lecture 7 Slide 25 Double Rainbow Diagrams

26. Physics 1051 Lecture 7 Slide 26 Double Rainbow Diagram

27. Physics 1051 Lecture 7 Slide 27 Many Raindrops Diagram

28. Physics 1051 Lecture 7 Slide 28 Alexander’s Dark Band Sky is light inside primary rainbow Dark between primary and secondary bows Light beyond the secondary rainbow Dark region between is called Alexander’s Dark Band

29. Physics 1051 Lecture 7 Slide 29 22 o Halo A halo is a ring of light surrounding the sun or moon. Most halos appear as bright white rings but in some instances, the dispersion of light as it passes through ice crystals found in upper level cirrus clouds can cause a halo to have color. dispersioncirrus Randomly oriented hexagonal ice crystals Diameter less than 20.5 micrometers

30. Physics 1051 Lecture 7 Slide 30 Sundogs Sundogs or parhelia on right and left of sun Flat faces horizontally oriented Hexagonal ice crystals Diameter greater than 30 micrometers

31. Physics 1051 Lecture 7 Slide 31 Sundog

32. Physics 1051 Lecture 7 Slide 32 Sundog

33. Physics 1051 Lecture 7 Slide 33 Sundog