Light and Optics

1
Light and Optics
2
25) analyze the properties of light and optics (GPS, HSGT) 25a) explain the relationship between energy, frequency, wavelength and velocity for all parts of the electromagnetic spectrum (GPS) 25b) use the speed of light in distance-time calculations (GPS) 25c) distinguish between the colors of the visible light spectrum emphasizing the frequency, wavelength and energy associated with the colors (GPS) 25d) distinguish between plane and diffuse reflection, and analyze the image formed by a plane mirror (GPS) 25e) investigate refraction of light in relation to the speed of light in media, index of refraction, and angles of incidence and refraction (Snells Law) (GPS) 25e1) solve problems involving the refraction of light in relation to the speed of light in media, index of refraction, and angles of incidence and refraction (Snells Law) (GPS)   25f) explain critical angle and its relationship to total internal reflection vs. refraction (GPS) 25f1) solve problems using critical angle and its relationship to total internal reflection vs. refraction (GPS) 25g) demonstrate interference and diffraction effects in a single slit, a double slit, and/or a multiple slit diffraction grating and thin film (include the relationship between spectra and atomic structure) (GPS) 25h) explain the polarization of light (GPS) 25i) demonstrate the dispersion of white light into a color spectrum and the addition of primary and secondary colors to form white light 25j) distinguish between the primary colors of light and the primary colors of pigments 25k) apply the principles of light to lasers, fiber optics, rainbows, and prisms (GPS) 25l) construct ray diagrams and make calculations relating to focal length, image distance, object distance and image magnification for curved mirrors and lenses (GPS) 25m) apply image formation to lenses, cameras, telescopes, flat and curved mirrors, and eyewear (GPS)
3
Section 1 Intro to Electromagnetic Waves

• Intro Questions
• What is the difference between mechanical and
  electromagnetic waves?
• Name as many types of electromagnetic waves you
  can
• What is the speed of light and any other
  electromagnetic wave in space?

4
The Electromagnetic Wave

• Characteristics
• Require no medium
• Transverse waves of oscillating electromagnetic
  fields
• Transverse waves move perpendicular to the
  direction the wave moves
• The electric and magnetic fields are at right
  angles to each other
• All electromagnetic waves travel at 3.0 x 108 m/s

Electric Field
Direction of travel towards you
Magnetic Field
5
The Electromagnetic Spectrum
Wavelength Decreases
Frequency Increases
Energy Increases
V ? f
3.0 x 108 ? f
More Penetration and Dangerous
Velocity 3.0 x 108 m/s For All Electromagnetic
Waves
6
Activity 1

1. Label all the parts of the electromagnetic
   spectrum in order of increasing frequency.
2. Radio Waves, Microwaves, Infrared, Visible Light,
   Ultra Violet, X-rays, Gamma Rays
3. Label the trend lines as well

7
Activity 1

1. Label all the parts of the electromagnetic
   spectrum in order of increasing frequency.
2. Radio Waves, Microwaves, Infrared, Visible Light,
   Ultra Violet, X-rays, Gamma Rays
3. Label the trend lines as well

4 Visible Light
3 Infrared
6 X-Rays
7 Gamma Rays
1 Radio waves
2 Microwaves
5 Ultra Violet
Wavelength Decreases
Frequency Increases
Energy Increases
More Penetration and Dangerous
8
Section 2 Electromagnetic Wave Math
9
Speed of light distance-time calculations
V ? f

• Velocity 3.0 x 108 m/s for all electromagnetic
  waves
• If you see any of these you have an
  electromagnetic wave and v 3.0 x 108 m/s
• Radio Waves, Microwaves, Infrared, Visible Light,
  Ultra Violet, X-rays, Gamma Rays

10
Example 1

• The AM radio band extends from 5.4 x 105 Hz to
  1.7 x 106 Hz. What are the longest and shortest
  wavelengths in this frequency range?

11
Example 1

• The AM radio band extends from 5.4 x 105 Hz to
  1.7 x 106 Hz. What are the longest and shortest
  wavelengths in this frequency range?

12
Example 2

• What is the frequency of an electromagnetic wave
  if it has a wavelength of 1.0 km?

13
Example 2

• What is the frequency of an electromagnetic wave
  if it has a wavelength of 1.0 km?

14
Example 3

• How long does it take for light from the sun to
  reach Earth if the sun is 1.5 x 1011 m away?

15
Example 3

• How long does it take for light from the sun to
  reach Earth if the sun is 1.5 x 1011 m away?

16
Intro

1. What are the primary colors of light?
2. List the colors of the rainbow in order
3. What do all the colors of the rainbow add up to?

17
Section 3 Visible Light and Colors
18
Visible Light

• Characteristics
• White light is a combination of red, orange,
  yellow, green, cyan, blue, and violet
• A prism can separate these colors out
• By refraction of different wavelengths of color

19
Visible Light
700 nm
400 nm
Red orange yellow green cyan blue
violet

• Red
• Longest Wavelength
• Lowest Frequency
• Least Energy

• Violet
• Shortest Wavelength
• Highest Frequency
• Most Energy

20
Activity 2

• List the colors of the rainbow in order from
  lowest to highest frequency
• Color this at home

Lowest Frequency
Highest Frequency
________ ________ ________ ________
________ ________ ________
Visible Light
21
Activity 2

• List the colors of the rainbow in order from
  lowest to highest frequency
• Color this at home

Lowest Frequency
Highest Frequency
Red orange yellow green cyan blue
violet
Visible Light
22

• Primary Colors
• Red
• Blue
• Green

Blue
Red
Green
23

• Secondary Colors Mixture of 2 Primary Colors
• Magenta (Blue and Red)
• Cyan (Blue and Green)
• Yellow (Red and Green)
• A mixture of all three primary colors produces
  white light

Blue
Red
Magenta
Blue
Green
Blue
Cyan
Blue
Red
Green
Green
Red
Yellow
White
24

• Primary Colors
• Red
• Blue
• Green

Blue
Red
Green
25

• Since secondary colors are a mix of two
  primaries
• Mixing primary and secondary colors produces
  white light
• White Light Primary Color Secondary Color
• White Light Blue Yellow
• White Light Green Magenta
• White Light Red Cyan

Blue
Red
Green
26
Activity 3

• Color and label the color mixture diagram

White Light Primary Color Secondary
Color White Light ___________
____________ White Light ___________
____________ White Light ___________
____________
27
Activity 3

• Color and label the color mixture diagram

White Light Primary Color Secondary
Color White Light Blue Yellow White Light
Green Magenta White Light Red Cyan
White
28

• Primary colors of light
• Primary pigments (ink)

Red
Blue
Green
Magenta
Cyan
Yellow
29

• Primary colors (light)
• Red
• Blue
• Green
• Primary pigments (ink)
• Magenta
• Yellow
• Cyan

are secondary pigments
Primary colors add up to white light
Red
Magenta
Yellow
Blue
Green
Cyan
are secondary colors
Primary pigments (ink) adds up to black
Yellow
Green
Red
Cyan
Magenta
Blue
30
Intro

• Do section 3 of your worksheets as your intro
  today

31
Section 4 Refraction of Light
32

• Optics is the science that describes the behavior
  and properties of light and the interaction of
  light with matter.

33

• Refraction- Bending of light as it travels from
  one medium to another.
• Refraction occurs because lights velocity changes
  in another medium.
• Light does not need a medium but it is affected
  by it.

34
Key items for refraction

• Light travels from the object to the observers
  eyes
• Light travels at different speed indifferent
  medium
• Terms to know
• Normal line
• Angle of incidence Ti
• Angle of refraction Tr

Normal Line
Tr
Slower Medium
Ti
35

part of it is reflected

• As light moves into a new medium,

and part is refracted
(a) Into slower medium light bends toward the
normal line
(b) Into faster medium light bends away from the
normal line
36

• Objects appear to be in a different position due
  to refraction
• An object appears to be straight ahead
• Light always travels from the object to the
  observers eyes, bending into the new medium

Cats Perspective
Fishes Perspective
37

• Index of refraction (n)- the ratio of speed of
  light in a vacuum to speed of light in that
  substance.
• Always greater than 1 because light in a vacuum
  is the fastest (n 1.00 for a vacuum)
• Has no unit
• n index of refraction
• c speed of light in a vacuum
• v speed of light in medium

 
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Example 4

• Tom, a watchmaker, is interested in an old
  timepiece thats been brought in for a cleaning.
  If light travels at 1.90 x 108 m/s in the
  crystal, what is the crystals index of
  refraction?

40
Example 4

• Tom, a watchmaker, is interested in an old
  timepiece thats been brought in for a cleaning.
  If light travels at 1.90 x 108 m/s in the
  crystal, what is the crystals index of
  refraction?

41
Example 5

• How fast does light travel in fluorite (n1.434)?

42
Example 5

• How fast does light travel in fluorite (n1.434)?

43

• Snell's Law- a formula that describes the angle
  of incidence and angle of refraction
• (ni)(sin Ti) (nr)(sin Tr)
• ni index of refraction of first medium
  (incidence side)
• Ti angle of incidence
• nr index of refraction of second medium
  (refracted side)
• Tr angle of refraction

44

• (ni)(sin Ti) (nr)(sin Tr)

Can be rearranged to solve for ni
Can be rearranged to solve for nr
 
 
45

• (ni)(sin Ti) (nr)(sin Tr)

Can be rearranged to solve for Ti
Can be rearranged to solve for Tr
 
 
46
Example 6

• A light ray traveling through air (n1.00)
  strikes a smooth, flat slab of crown glass
  (n1.52) at an angle of 30.0 to the normal.
• Find the angle of refraction
• Draw a picture and label it

47
Example 6

• A light ray traveling through air (n1.00)
  strikes a smooth, flat slab of crown glass
  (n1.52) at an angle of 30.0 to the normal.
  Find the angle of refraction.

48
Example 7

• Find the angle of refraction for a ray of light
  that enters a calm lake at an angle of 25 to the
  normal. (nair 1.00 and nwater 1.33)

49
Example 7

• Find the angle of refraction for a ray of light
  that enters a calm lake at an angle of 25 to the
  normal. (nair 1.00 and nwater 1.33)

50
Section 5 Critical Angle
51

• What happens when you increase the angle of
  incidence when going from a slow to a fast
  medium?
• Remember slow to fast bends away from the normal
• What happens if you increase the angle of
  incidence beyond here?
• Total internal reflection

Tr
nr 1.00 (faster)
ni 1.33 (slower)
Ti
52
Click on the picture for a critical angle
animation
53

• Critical angle- Angle at which there would be no
  refraction only total internal reflection.
• Critical angle equation (?c critical angle)

 
 
Tr
nr 1.00 (faster)
ni 1.33 (slower)
Ti
54
Example 8

• A jeweler must decide whether the stone in Mrs.
  Harders ring is a real diamond or a
  less-precious zircon. He measures the critical
  angle of the gem and finds that it is 31.3. Is
  the stone really a diamond or just a good
  imitation? (ndiamond 2.41, nzircon 1.92,
  nair 1.00 )

nair always the smaller n in critical angle
problems
 
n in question solve for this
55
Example 8

• A jeweler must decide whether the stone in Mrs.
  Harders ring is a real diamond or a
  less-precious zircon. He measures the critical
  angle of the gem and finds that it is 31.3. Is
  the stone really a diamond or just a good
  imitation? (ndiamond 2.41, nzircon 1.92,
  nair 1.00 )

56
Intro

• Work on section 5 and 6 of your worksheets

57
Intro

• Study for your quiz a few minutes
• Borrow a ruler if you do not have one today and
  tomorrow. Return them before the quiz
• The quiz will take place after our lesson today

58
Section 6 Reflection and Intro to Mirrors
59

• Why can you see a reflection on the surface of
  one object
• It depends on how smooth the surface is

but not on the surface of another?
Light is reflected all over here
Light is reflected in the same direction here
60
Reflections

• Planar reflection -off of a smooth surface
• Diffuse reflection - reflection off of a rough of
  textured surface.

Planar reflection
Diffuse reflection
61
Types of Mirrors

• Plane Mirror flat mirror
• Concave mirror - curved in the reflecting
  surface is inside the sphere
• Convex mirror - curved out the reflecting
  surface is outside the sphere

Convex Mirror
Plane Mirror
cave
Concave Mirror
62
Plane Mirrors

• A plane mirror is a flat mirror
• Plane mirrors produce images that are
• Virtual - image that appears behind the plane of
  the mirror.
• Upright Up in the mirror is the same as the
  object
• Non-magnified Appear the same size as if the
  object was that distance away
• Reversed

63

• Concave (Converging) mirror
• Produce two types of images depending on where
  the object is located relative to the focal point
• Real inverted images (object beyond focal point)
• Magnified virtual upright images (object between
  focal point and surface of mirror)

64

• Concave (converging) mirror
• Why two names?
• Concave name because of shape
• Converging name because of what light does
• bends inward or converges

Bends inward toward the object
65

• Convex (diverging) mirror
• Only produce virtual, upright, and smaller images

66

• Convex (diverging) mirror
• Why two names?
• Convex name because of shape
• Diverging name because of what light does
• bends outward or diverges

Bends outward away from the object
67

• What kind of mirror would water act like?
• Why? (What kind of image is formed here)

68

• What kind of mirror would this be like?
• Why? (What kind of image is formed here)

69

• What kind of mirror would this be like?
• Why? (What kind of image is formed here)

70
Section 7 Planar Ray Diagram
71
A Ray Diagram

• A drawing allows you to determine the size and
  orientation of an image formed with a mirror or
  lens.
• The real side of the mirror is the side the
  object is on

Mirror
The real side of a mirror
The virtual side of a mirror
72
Activity 4 Drawing a Ray Diagram in a planar
mirror

• 1. First draw the object, the mirror plane, label
  p and h. (the object is traditionally drawn as
  an arrow)
• do is the distance to the mirror from the object
• ho is the height of the object

do
ho
Object
73
Drawing the Rays

• Draw a ray perpendicular to the mirrors surface
  and include its reflection
• Draw a single ray going at an angle away from the
  object to the mirror (Include its reflection)
• Since the rays dont cross on the real side of
  the mirror, after the reflection, extend them
  until they meet on the virtual side.
• This is where the image would appear, draw the
  image, with the top being where the rays
  intersect
• Then finish the labeling

di
do
1
3
2
hi
ho
4
Object
74
Variables you need to know

• do is the distance to the mirror from the object
• di is the distance from the mirror to the image
  of the mirror
• ho is the height of the object
• hi is the height of the image

di
do
hi
ho
Object
Image
75
Now we can analyze the image

• The image formed in a planar mirror is
• Virtual
• Same size
• Upright

ho and hi are equal
Virtual on this side of a mirror
di
do
1
3
2
hi
ho
4
Object
Facing up
76
Example 9

• Law of Reflection Review
• Mary sees a reflection of her cat sparkles in the
  living room window. The image of Sparkles makes
  an angle of 40 with the normal, at what angle
  does Mary see Sparkles reflected?

Tr ?
Ti 40
77
Example 9

• Law of Reflection Review
• Mary sees a reflection of her cat sparkles in the
  living room window. The image of Sparkles makes
  an angle of 40 with the normal, at what angle
  does Mary see Sparkles reflected?

At 40 to the normal line
Tr 40
Ti 40
78
Intro

• a. __________________ What is line C called
  above?
• b. __________________ What would be the angle or
  reflection be in the diagram above?
• c. __________________ What would be the angle of
  refraction be in the diagram above?
• d. __________________ What would be the critical
  angle above be for the light beam in a
  substance(n1.59) shown above?

79
Intro

• a. __________________ What is line C called
  above?
• b. __________________ What would be the angle or
  reflection be in the diagram above?
• c. __________________ What would be the angle of
  refraction be in the diagram above?
• d. __________________ What would be the critical
  angle above be for the light beam in the
  substance (n1.59) shown above?

80
Section 8 Concave Mirror Ray Diagram
81
Curved Mirror Ray Diagram

• More variables you need to know for a curved
  mirror
• Center of curvature (C) the center of the curve
  if it was a sphere
• Focal Point (F) ½ from the mirror to the center
  of curvature
• Principal axis- the line that the base of the
  arrow is on.

Principal axis
C
F
82
Rules for Drawing Reference Rays (Concave Mirror) Rules for Drawing Reference Rays (Concave Mirror) Rules for Drawing Reference Rays (Concave Mirror)
Ray Line drawn from object to mirror Line drawn from mirror to image after reflection
1. Parallel to principal axis Through focal point F
2. Through focal point F Parallel to principal axis
C
F
The image appears where all rays intersect
Activity 5
83

• Now analyze the image just formed
• Its
• Smaller (hi is less than ho)
• Inverted (upside down)
• Real (on the object side of a mirror)

object
ho
hi
image
Activity 5
84

• A convex mirror produces many different types of
  images
• Click picture for concave mirror animation

85
Rules for Drawing Reference Rays (Concave Mirror) Rules for Drawing Reference Rays (Concave Mirror) Rules for Drawing Reference Rays (Concave Mirror)
Ray Line drawn from object to mirror Line drawn from mirror to image after reflection
1. Parallel to principal axis Through focal point F
2. Through focal point F Parallel to principal axis
C
F
The image appears where all rays intersect
Activity 5
86

• Now analyze the image just formed
• Its
• Not magnified (ho hi)
• Inverted (upside down)
• Real (on the object side of a mirror)

object
ho
C
F
image
Activity 5
87
Rules for Drawing Reference Rays (Concave Mirror) Rules for Drawing Reference Rays (Concave Mirror) Rules for Drawing Reference Rays (Concave Mirror)
Ray Line drawn from object to mirror Line drawn from mirror to image after reflection
1. Parallel to principal axis Through focal point F
2. Through focal point F Parallel to principal axis
C
F
The image appears where all rays intersect
Activity 5
88

• Now analyze the image just formed
• Its
• magnified (ho lt hi)
• Inverted (upside down)
• Real (on the object side of a mirror)

object
ho
C
F
hi
image
Activity 5
89
Rules for Drawing Reference Rays (Concave Mirror) Rules for Drawing Reference Rays (Concave Mirror) Rules for Drawing Reference Rays (Concave Mirror)
Ray Line drawn from object to mirror Line drawn from mirror to image after reflection
1. Parallel to principal axis Through focal point F
2. Through focal point F Parallel to principal axis
C
F
Activity 5
90

• Now analyze the image just formed
• Its
• No image formed
• Does not intersect on the real or virtual side

C
F
Activity 5
91
Rules for Drawing Reference Rays (Concave Mirror) Rules for Drawing Reference Rays (Concave Mirror) Rules for Drawing Reference Rays (Concave Mirror)
Ray Line drawn from object to mirror Line drawn from mirror to image after reflection
1. Parallel to principal axis Through focal point F
2. Through focal point F Parallel to principal axis
C
F
Activity 5
92

• Now analyze the image just formed
• Its
• magnified (ho lt hi)
• upright
• Virtual (on the virtual side of a mirror)

image
object
hi
ho
C
F
Activity 5
93
Section 9 Convex Mirror Ray Diagram
94
Rules for Drawing Reference Rays (convex mirror) Rules for Drawing Reference Rays (convex mirror) Rules for Drawing Reference Rays (convex mirror)
Ray Line drawn from object to mirror Line drawn from mirror to image after reflection
1. Parallel to principal axis Through focal point F (away from the mirror)
2. Through focal point F Parallel to principal axis
3. Follow the arrow tips away from the mirror back with virtual lines until they intersect Follow the arrow tips away from the mirror back with virtual lines until they intersect
C
F
This is where the image appeared
Activity 6
95

• Now analyze the image just formed
• Its
• Smaller (hi is less than ho)
• Upright
• Virtual (on the other side of a mirror)
• A convex mirror always produces this type of image

This is where the image appeared
96
Intro

• Do the following ray diagrams
• 1.
• 2.

F
C
F
C
97

• 3. List the objects that are
• Plane Mirrors
• Concave Mirror
• Convex Mirrors

98
Section 10 Mirror Math
99
Lens/ Mirror Math Cheat SheetTake out a piece of
paper and copy all of this
100
Mirror Math Equations
 
 
 
If M is negative then the image is inverted
101

• The object side is always positive for lenses and
  mirror math
• The image sign depends on image location
• The image here would have a positive value
• The image here would have a negative value

do
di
di
Positive object side
Positive image side of mirror
Positive focal side of mirror
102

• The focus is on the side of the center of
  curvature
• The concave mirror always curves to the real
  side and has a positive F

F
Positive focal side of mirror
103

• The focus is on the side of the center of
  curvature
• The convex mirror always curves to the virtual
  side and has a negative F

F
Positive focal side of mirror
104
Example 10

• A concave mirror has a focal length of 10.0 cm.
  Locate the image of a pencil that is placed
  upright 30.0 cm from the mirror.
• Find the magnification of the image.
• Draw a ray diagram of the situation

 
F
C
 
105
Example 10

• A concave mirror has a focal length of 10.0 cm.
  Locate the image of a pencil that is placed
  upright 30.0 cm from the mirror.
• Find the magnification of the image.

 
 
106
Example 10

• A concave mirror has a focal length of 10.0 cm.
  Locate the image of a pencil that is placed
  upright 30.0 cm from the mirror.
• b. Draw a ray diagram of the situation

F
C
107
Example 11

• Mark is polishing his crystal ball. He sees his
  reflection as he gazes into the ball from a
  distance of 15 cm.
• what is the focal length of Marks crystal ball
  if he sees her reflection 4.0 cm behind the
  surface?
• Is the image real or virtual

108
Example 11

• Mark is polishing his crystal ball. He sees his
  reflection as he gazes into the ball from a
  distance of 15 cm.
• what is the focal length of Marks crystal ball
  if he sees her reflection 4.0 cm behind the
  surface?
• Is the image real or virtual

 
109
Example 12

• You look into an empty water bowl from 6.0 cm
  away and see a reflection 12 cm behind the bowl.
• What is the focal length of the bowl?
• What is the magnification of the image?

110
Example 12

• You look into an empty water bowl from 6.0 cm
  away and see a reflection 12.0 cm behind the
  bowl.
• What is the focal length of the bowl
• What is the magnification of the image?

 
 
111
Intro

• Mark looks into a concave mirror from 5 cm away.
  If the image appears 10 cm behind the mirror
• What is the magnification?
• What is the focal length?

112
Section 11 Intro to Lenses
113
The Lens Movie Clip
114
Types of lenses

• Convex (converging) lens
• Concave (diverging) lens
• Name for what light does is opposite of mirrors

115

• Convex (converging) Lens
• Why two names?
• Convex name because of shape
• converging name because of what light does
• bends inward or converges

Near side bends outward away from the object
116

• Concave (diverging) Lens
• Why two names?
• Concave name because of shape
• Diverging name because of what light does
• bends outward or diverges

Near side bends inward toward the object
117
The Lens

• do distance to object
• di distance to image
• ho height of object
• hi height of image
• F virtual focal point
• 2F double virtual focal point
• F focal point
• 2F double focal point

do
di
ho
Object
2F
F
Image
F
2F
hi
Real side in lenses
Virtual side in lenses
118
Section 12 Concave Lens Ray Diagram
119
Rules for Drawing Reference Rays (concave/diverging lens) Rules for Drawing Reference Rays (concave/diverging lens) Rules for Drawing Reference Rays (concave/diverging lens)
Ray Line drawn from object to lens Line drawn from mirror to image after refraction
1. Parallel to principal axis Through focal point F
2. Through center of lens Continue straight
3. Follow the arrow tips back to the virtual side where they intersect Follow the arrow tips back to the virtual side where they intersect
Activity 7
2F
F
F
2F
The image appears where all rays intersect
120
Concave/diverging lens

• Always produces a
• Virtual
• Upright
• Smaller image

121
Section 13 Convex Lens Ray Diagram
122
Rules for Drawing Reference Rays (convex/converging lens) Rules for Drawing Reference Rays (convex/converging lens) Rules for Drawing Reference Rays (convex/converging lens)
Ray Line drawn from object to lens Line drawn from mirror to image after refraction
1. Parallel to principal axis Through focal point F
2. Through center of lens Continue straight
3. Place the image head where the rays intersect or trace the rays to the virtual side if they dont intersect Place the image head where the rays intersect or trace the rays to the virtual side if they dont intersect
2F
F
F
2F
Activity 8
123
Convex/converging lens

• Image produced
• Outside focal point (F)
• Real and inverted
• Outside 2F smaller
• At 2F same size
• Between 2F and F magnified
• Inside focal point (F)
• Virtual and upright

F
F
124
Section 14 Lens Math
125
Lens Math
 
 
126

• The object side is always positive for lenses and
  mirror math
• The virtual and real image sides are different
  for lenses
• The other side of the lens is positive for the
  image
• The image here would have a positive value
• The image here would have a negative value

di
do
do
di
Positive object side Negative image side
Positive image side of lens
127

• To determine the sign of the focal point
• Determine which way the front of the lens curves
  or just remember these two facts
• A convex lens always has a positive focal length
• Curves to the real side of a lens
• A concave lens always has a negative focal length
• Curves to the virtual side of a lens

Negative image and focal side of lens
Positive image and focal side of lens
128
Example 13

• When Sally holds a convex lens 1.00 m from a
  snow-covered wall, an image of a 5.00 m distant
  igloo is projected onto the snow.
• What is the focal length of the lens?
• Draw a ray diagram of the situation

F
F
 
129
Example 13

• When Sally holds a convex lens 1.00 m from a
  snow-covered wall, an image of a 5.00 m distant
  igloo is projected onto the snow.
• What is the focal length of the lens?

 
130
Example 13

• When Sally holds a convex lens 1.00 m from a
  snow-covered wall, an image of a 5.00 m distant
  igloo is projected onto the snow.
• b. Draw a ray diagram of the situation

F
F
131
Example 14

• A concave lens is placed 5.0 cm in front of a
  doll.
• What is the focal length of the lens if the
  dolls image appears 2.0 cm on the same side of
  the lens?
• Draw a ray diagram of the situation

F
F
132
Example 14

• A concave lens is placed 5.0 cm in front of a
  doll.
• What is the focal length of the lens if the
  dolls image appears 2.0 cm on the same size of
  the lens?

 
133
Example 14

• A concave lens is placed 5.0 cm in front of a
  doll.
• What is the focal length of the lens if the
  dolls image appears 2.0 cm on the same size of
  the lens?
• Draw a ray diagram of the situation

F
F
134
Example 15

• A coin collector is looking at a rare coin 1.0 cm
  behind a magnifying glass (convex lens) with a
  focal length of 5.0 cm.
• What is the distance to the image?
• What is the images magnification?

135
Example 15

• A coin collector is looking at a rare coin 1.0 cm
  behind a magnifying glass (convex lens) with a
  focal length of 5.0 cm.
• What is the distance to the image?

 
136
Example 15

• A coin collector is looking at a rare coin 1.0 cm
  behind a magnifying glass (convex lens) with a
  focal length of 5.0 cm.
• What is the distance to the image?
• What is the images magnification?

 
 
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137
Intro

• You are looking at yourself from 5cm away in a
  concave mirror that has a focal length of 15cm.
• What is the distance to the image?
• What is the magnification?
• 2. You do the same as in 1 but in a convex
  mirror
• What is the distance to the image?
• What is the magnification?
• 3. You are looking through a convex lens at an
  object 5cm away. The image is projected 15 cm
  on the same
• What is the focal length of the lens?
• What is the magnification?

138
Intro

• You are looking at yourself from 5cm away in a
  concave mirror that has a focal length of 15cm.
• What is the distance to the image?
• What is the magnification?

139
Intro

• 2. You do the same as in 1 but in a convex
  mirror
• What is the distance to the image?
• What is the magnification?

140
Intro

• 3. You are looking through a convex lens at an
  object 5cm away. The image is projected 15 cm
  on the same
• What is the focal length of the lens?
• What is the magnification?

141

• 4. A ray of light is coming from a penny at the
  bottom of the water and hitting the surface at an
  angle of 34? what is the angle of refraction.
  (nair 1.00 nwater 1.33)

142

• 4. A ray of light is coming from a penny at the
  bottom of the water and hitting the surface at an
  angle of 34? what is the angle of refraction.
  (nair 1.00 nwater 1.33)

143

• 4. A ray of light is coming from a penny at the
  bottom of the water and hitting the surface at an
  angle of 34? what is the angle of refraction.
  (nair 1.00 nwater 1.33)

144
Section 15 Common Optical Instruments
145
Common Optical Instruments

• Camera- A simple camera consists of a convex lens
  and a light sensitive film
• The diaphragm and shutter regulates how much
  light gets to the film.
• The diaphragm controls the size of opening the
  light passes through
• Most cameras use more than one lens today

146
Common Optical Instruments

• Telescope- Uses two lenses to enlarge an image
  far away.
• You see an image of an image. The eyepiece lens
  forms an enlarged virtual image of the real image
  formed by the objective lens.

147
The Eye

• How the eye focuses
• The ciliary muscle around the eye changes the
  shape and thickness of the lens, which changes
  the focal length of the lens
• In both cameras and the eye the image is
  inverted. The brain has learned to turn the
  image around.

148
Defects in Vision

• Farsighted (Hyperopia)- trouble focusing on
  objects close. The eyeball is too short or the
  cornea is too flat.
• Focus is behind the retina without correction

149
Defects in Vision

• Nearsighted (Myopia)- trouble focusing on objects
  far away. The eyeball is too long or the cornea
  is too curved.
• Focus is in front of the retina

150
Fixing defects

• Converging/convex lenses are used to correct
  farsightedness.
• Diverging/concave lenses are used to correct
  nearsightedness.

151
Section 15 Dual Nature of Light
152
Dual Nature of LightWave Particle Duality

• Light acts as a wave (through space) and a
  particle (when it interacts with matter)
• Waves are energy carried in the disruption of
  medium. Have interference patterns when they go
  through each other.
• Particles have a mass and could not occupy the
  same space.

153
Remember Interference

• Within an interference pattern wave amplitudes
  may be increased, decreased, or neutralized

Constructive Interference Causes Reinforcement
Destructive Interference Causes Cancelation
154
Interference with Waves in Water

• Reinforcement and cancelation can be seen here

155

• Huygens Principle
• Huygens states light acts as a wave
• Every point acts as a source of a new wave

156

• Wave Properties of Light
• Single slit diffraction on visible light.
• Light has Huygens property of a wave
• Light fans out and actually appears wider than it
  should be.

157
Youngs Interference Experiment

• Young further demonstrate the wave properties of
  light with a double slit film.
• When a monochromatic light source is used a
  pattern of fringes result

158

• Young shows that light has interference based on
  its wave properties

159
Particle Nature of Light

• Light acts like a stream of particles when it
  interacts with matter
• Photoelectric Effect- Ejection of electrons from
  certain metals when light falls upon them.
• Requires a high frequency of light

160
Dual Nature of Light Video Clip
161
Section 16 Other Light Phenomenon
162
Laser Light

• Incoherent light- crests and troughs dont line
  up
• Coherent light- crests and troughs line up (same
  frequency, phase, and direction)
• Laser- Produces coherent light with the aid of a
  crystal

Laser Light
163
Light sabers and Laser beams
164
Rainbows are produced by the refraction of light
165
Thin Films

• Light from one side of a bubble cancels out light
  from the other side showing color from white light

166

• Diffraction Grating can be used to disperse light
  into colors like a prism
• A prism used refraction to disperse light
• Diffraction gradients use the interference of
  light to produce colors

167
Diffraction and Polarization Clip
168
Polarization of Light

• Light is an electromagnetic wave
• These waves produce an electric field at a right
  angle to the magnetic field
• Usually the rays are unpolarized which means they
  are oscillating in random directions.

169
Polarized Light

• Some crystals can cause unpolarized light to pass
  through and produce polarized light which has its
  electromagnetic fields aligned in the same
  direction.
• Transmission axis- line along which light is
  polarized

170

• Transmission axis- line along which light is
  polarized
• Light at 90º to the transmission axis cannot pass
  through.

171
How polarized sunglasses work

• Glare
• When light reflects off the ground (a horizontal
  surface) it is polarized horizontally.
• Sunglasses stop glare
• They are polarized vertically so that horizontal
  glare cannot get through