1. HW #3, Due Sep. 14
Chapter 2
P23, P24, PH13, PH15, PM2

2. Undergraduate Research Opportunity
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3. Lecture 7 (chapter 2 continued)
Quick Review:
Refraction
Total Internal Reflection
This Lecture:
Refraction in Nature (Mirages, Halos, Rainbows,..)
Chapter 3 (Lenses and Mirrors)?

4. Refraction Recall: velocity of light v= c/n

6. *Refraction 1
Fish Tank

7. Material Refractive Index (n) Air 1.0003
Examples
Material Refractive Index (n)
Air
Water
Glycerin
Immersion Oil
Glass 1.52
Flint
Zircon
Diamond
Silicon 4

8. Law of Refraction i r R I Air (for example) glass or water or … N n1
The Refracted ray (R ) lies in the plane defined by Incidence ray (I) and surface Normal (N)
The Refracted ray (R ) lies on the opposite side of N as the incident ray I, and
The Refracted ray (R ) makes an angle r that satisfies the Snell’s law:
Angle of Incidence  Index of refraction in medium 1
almost equals to
Angle of Refraction  Index of refraction in medium 2
(for small angles)

9. Snell’s Law (exact) c a 
Sine of an angle

10. Now, consider this ….

11. Total Internal Reflection
*Total Internal Reflection (Optical Fiber)

12. Total Internal Reflection

13. Prisms as perfect reflectors:
See Fig in the Text

14. Brilliance (TIR), Fire (dispersion) and Flash
Diamond
Brilliance (TIR), Fire (dispersion) and Flash

15. Mirages, Rainbows, Halos, Sun Dogs….
Next
Refraction in Nature
Mirages, Rainbows, Halos, Sun Dogs….

16. Mirages and Atmospheric Distortions
sunset
mirage

17. Mirage

18. Dispersion Refractive Index varies with Wavelength : n()
Dispersion in a prism
* Prism Refraction
refraction & refl.
dispersion

19. Rainbow

20. Rainbow *Rainbow http://www.phy.ntnu.edu.tw/java/Rainbow/rainbow.html
rain drop

23. Ice Crystals

24. Sun Dogs

29. Halos

31. 22 degree halo

32. 22 degree halo

33. 46 degree halos

34. Chapter 3 Mirrors and Lenses
Read , 3.2, 3.3 (A, B, C* , D), 3.4, 3.5**
* Anamorphic Art
** Aberrations

35. Flat mirror revisited
virtual
image
Read Text about the Kaleidoscope

36. (simply apply the law of reflection)
Spherical Mirrors
Where is the image?
What is the field of view?
Ray Tracing
(simply apply the law of reflection)

37. Reflection in Curved Mirrors
Convex and Concave
Mirrors

38. axis O C F center focal point
Paraxial Rays: Rays that are close to the axis

39. Ray Rules for a Convex Mirror
Ray Rule 1: All rays incident parallel to the axis are reflected so
that they appear to be coming form the the focal point, F.
Ray Rule 2: All rays that (when extended) pass through center C
are reflected back to themselves.
Ray Rule 3: All rays that (when extended) pass through F are
reflected back parallel to the axis.

40. C F O 1 C F O 3 C F O 2

41. Locating the Image Mirrors *Concave Mirrors
*Concave Lens: virtual image
*Convex Mirrors
spherical aberration

43. “Hand with Reflecting Globe”
M. C. Escher,
“Hand with Reflecting Globe”
Fig 3.9

44. Concave Mirror
axis O C F
center
focal point

45. Ray Rules for a Concave Mirror
Ray Rule 1: All rays incident parallel to the axis are reflected so
that they appear to be coming form the the focal point, F.
Ray Rule 2: All rays that (when extended) pass through center C
are reflected back to themselves.
Ray Rule 3: All rays that (when extended) pass through F are
reflected back parallel to the axis.

46. *Concave Mirrors

47. Lenses

48. *Magnification (Magnifying Glass)
* Lens Action (Many Applets)
principle rays
*Thick Lens (Spherical Aberration)

49. Fresnel Lenses