1. Physics
Chapter 15:
Refraction

2. Refraction In Air: c = 3x108 m/s
In Other Materials Light Travels Slower than c (slightly)
The Speed of Light Will Change When Passing From One Material to Another
When this Change Occurs The Direction of the Light Also Changes

3. Refraction Refraction
The Bending of Light Rays as it Passes from One Medium to Another

4. Refraction Refraction
The Direction of Light Changes due to a Change in the Velocity of Light Caused by the Light Rays Passing From One Material to Another

5. Refraction Refraction of Light Rays qi qr Air Glass qR
Refraction Toward Normal

6. Refraction Refraction of Light Rays qi qr Glass Air qR
Refraction Away From Normal

7. Refraction
Refraction of Light Waves

8. Refraction Frequency Remains Constant through Varying Light Velocities
Wavelength (l) will Fluctuate
Smaller when Light is Slowed
Larger when Light is Accelerated

9. Refraction Refractive Index (n)
Ratio of the Velocity of Light in a Material Compared to The Speed of Light in a Vacuum

10. Refraction Refractive Index (n)
The Higher the RI, the Lower the Velocity of Light Through the Media

11. Refraction Refractive Index (n) Materials Solids Diamond 2.419
NaCl
Crown Glass
Ice

12. Refraction Refractive Index (n) Materials Liquids CS2 1.628
Benzene 1.501
CCl
EtOH
H2O

13. Refraction Refractive Index (n) Materials Gases CO2 1.00045
Air O H

14. Refraction of Light Rays
When a Light Ray Encounters an Interface Between Transparent Materials Some of the Light is Reflected, but Some of the Light Passes Through the Transparent Material

15. Refraction Refraction of Light Rays qi qr Air n=1 Glass n=1.523
Lower RI to Higher RI
Velocity Decreases
Refraction Toward Normal qR

16. Refraction Refraction of Light Rays qi qr Glass n=1.523 Air n=1 qR
Higher RI to Lower RI
Velocity Increases
Refraction Away From Normal

17. Refraction Refraction of Light Rays
This Change in the Path of the Light Rays Distorts Our Perception of the Location of an Image Viewed Through an Interface

18. Refraction
Refraction of Light Rays

19. Refraction
Example:
What angle should the light be aimed to find the sunken treasure chest?

20. Refraction
Solution:

21. Refraction
Refraction of Light Rays
Snell’s Law of Refraction q1 q2

22. Refraction Snell’s Law of Refraction (Example):
Light shining into an aquarium passes from air through glass at an angle of 150 from normal and then into water. What is the final refracted angle into the water? q1 q2

23. Refraction
Solution: Glass
n1 = 1.0
q1 = 150
n2 = 1.5
q2 = ? q1 q2

24. Refraction
Solution: Water
n1 = 1.5
q1 = 9.90
n2 = 1.3
q2 = ? q1 q2

25. Refraction
Problem:
Let’s assume in the last problem that you are looking at your pet piranha in your aquarium. The piranha is 4 inches from the 0.25” thick glass in the aquarium. What is the distance that the image is shifted from its actual position? q1 q2

26. Refraction
Solution:
0.25”
You 4”
150
9.90
11.50
Fish q1 q2

27. Refraction
Solution: Glass Up
5.10
.25” q1 q2

28. Refraction
Solution: Water Up
3.50 4” q1 q2

29. Refraction Solution: Net 0.022” Up + 0.245” Up = 0.267” Displacementq1 q2

30. Refraction Homework: Page 587 Problems: 10 (30.3o) 11 (26o) 13 ?
14 (q1 = 30.4o, q2 = 22.3o)

31. Refraction Lenses Made from Transparent Materials Refract Light
Form an Image of the Light Source

32. Refraction Lenses Converging Lens
Paraxial Incident Rays Converge at a Focal Point

33. Refraction Lenses Diverging Lens
Paraxial Incident Rays Diverge after Leaving Lens

34. Refraction
Lenses

35. Refraction Ray Diagrams – Converging Lenses Ray 1
Starts At Top of Object Running Parallel to Principal Axis
At Lens Center Crosses to Focal Point and Continues

36. Refraction Ray Diagrams – Converging Lenses Ray 2
Starts At Top of Object Running Through Focal Point to Lens Center
At Lens Center Crosses Continues Parallel to Principal Axis

37. Refraction Ray Diagrams – Converging Lenses Ray 3
Starts At Top of Object Running Through Center of Lens

38. Refraction Ray Diagrams – Converging Lenses
The Junction of these Rays Indicates the Type, Position, and Size of the Image

39. Refraction Image Formation by Converging Lenses
Image Qualities Depend on Object/Lens Position
Object Twice the Focal Length (F) from Lens
Object Between 2F and F from the Lens
Object Within the Focal Length from the Lens

40. Refraction Image Formation by Converging Lenses
Object Twice the Focal Length (F) from Lens
Image is Real
Image is Inverted
Image is Reduced

41. Refraction Image Formation by Converging Lenses
Object Between 2F and F from the Lens
Object is Real
Object is Inverted
Image is Enlarged

42. Refraction Image Formation by Converging Lenses
Object Within the Focal Length from the Lens
Image is Virtual
Image is Upright
Image is Enlarged

43. Refraction Image Formation by Diverging Lenses Image is Virtual
Image is Upright
Image is Reduced

44. Refraction Thin Lens Equation f = Focal Length of the Lens
d0 = Distance Between the Object and the Lens
di = Distance Between the Image and the Lens
Look Familiar? It should, It’s the Same as the Mirror Equation from Chapter 14

45. Refraction Magnification Equation m = Magnification hi = Image Height
ho = Object Height
Look Familiar? It should, It’s the Same as the Magnification Equation from Chapter 14

46. Refraction Multiple Lenses
Combinations Using Ocular and Objective Lenses
The Image Created by the First Lens Acts as the Object for the Second Lens

47. Refraction
Problem:
A ray of sunlight is passing from diamond into crown glass. The angle of incidence is 35.00o. The indices of refraction for the blue and red components of the ray are: blue (nd = 2.444, ncg=1.531), and red (nd = 2.410, ncg=1.520). What is the angle between the refracted blue and red rays in the crown glass?

48. Refraction Solution: q1 = 35.00o nd blue = 2.444 ncg blue = 1.531
nd red = 2.410
ncg red = 1.520

49. Refraction Solution: q1 = 35.00o nd blue = 2.444 ncg blue = 1.531
nd red = 2.410
ncg red = 1.520

50. Refraction Solution: q1 = 35.00o nd blue = 2.444 ncg blue = 1.531
nd red = 2.410
ncg red = 1.520

51. Refraction
Problem:
When a diverging lens is held 13cm above a line of print, the image is 5.0cm beneath the lens. What is the focal length of the lens?

52. Refraction
Solution:
do = -13cm
di = -5.0cm

53. Refraction
Problem:
A movie camera has a converging lens with a focal length of 85.0mm. It takes a picture of a 145cm tall person standing 16.0m away. What is the height of the image on the film and is the image upright or inverted?

54. Refraction
Solution:
ho = 145cm
f = 85x10-3m
do = 16.0cm
di = ?

55. Refraction
Solution:
ho = 145cm
f = 85x10-3m
do = 16.0cm
di = m

56. Refraction
Solution:
ho = 145cm
f = 85x10-3m
do = 16.0cm
di = m

57. Refraction Homework: Page 588 Problems:
24 (a, -13.3cm, M= b, -10.0cm, M=0.5 c, -6.67cm, M=0.667)
25 (3.40)
26 (a, 40.0cm, M= b, -20.0cm, M=2.0)

58. Refraction Total Internal Reflection
Refraction from Larger n to Smaller n
(ex. Water to Air)
Refraction is AWAY FROM NORMAL
q2 = 900 Critical Angle)
Any Increase in q1 Causes Total Internal Reflection

59. Refraction
Total Internal Reflection

60. Total Internal Reflection
Refraction
Total Internal Reflection
Fiber Optics
Core (n1) is Larger than Sheath (n2)
Design is Such That Any Bend the Cable Can Make is Within qc
This Keeps the Light Reflecting Within the Cable!

61. Refraction
Problem:
A ray of light originates in medium “A” and is incident upon medium “B.” What is the critical angle for each pair?
A B

62. Refraction Total Internal Reflection Solution: Critical Angle A B

63. Refraction Total Internal Reflection Solution: Critical Angle A B

64. Refraction Total Internal Reflection B must be smaller than A!
Solution: Critical Angle
A B
B must be smaller than A!

65. Refraction
Problem:
If the Glass in the Illustration is Surrounded by Air, At Which Point (A, B, or C) Will the Laser Beam Exit the Glass?

66. Refraction
Solution:
A = 600
B = 300***
C = 600

67. Refraction
Problem:
What If the Glass in the Illustration is Surrounded by Water, Where Will the Laser Beam Exit the Glass Then?

68. Refraction
Solution:
A = 600***
B = 300
C = 600

69. Refraction The Dispersion of Light – Prisms
Remember, Frequency is Constant
Wavelength will Change when Light is Refracted
When Light Enters a Prism (n1<n2)
Refraction Toward Normal
When Light Leaves a Prism (n1>n2)
Refraction Away From Normal
Wavelengths are Dispersed

70. Refraction
The Dispersion of Light – Prisms

71. Refraction The Dispersion of Light – Prisms
Light Must Encounter Two Different Refractive Indices for Refraction to Occur

72. Refraction
Problem:
A beam of sunlight is directed into a prism at the correct incident angle to produce refraction. However, the light passes directly through the prism without being refracted. What could cause this?

73. Refraction
Solution:
Light Must Encounter Two Different Refractive Indices for Refraction to Occur. If the prism were immersed in a fluid with the same refractive index as the glass that the prism is constructed, there would be no refraction and the light would pass through as if the prism were not there.

74. Refraction
Problem:
The prism in the picture is made of ice (n=1.31) and surrounded by oil (n=1.48). The light enters the prism horizontally. What is the angle of the exiting light to normal?

75. Refraction
Solution: Ice
qi = 270
n1 =1.48
n2 =1.31

76. Refraction
Solution: Oil
qi = 240
n1 =1.31
n2 =1.48

77. Homework: Page 589 Refraction Problems: 36 (42.8o)
37 (a, 31.3o b, 44.2o c, 49.8o)
38 ?