Preview

1
Section 1 Characteristics of Light
Chapter 13
Preview

• Objectives
• Electromagnetic Waves

2
Objectives
Section 1 Characteristics of Light
Chapter 13

• Identify the components of the electromagnetic
  spectrum.
• Calculate the frequency or wavelength of
  electromagnetic radiation.
• Recognize that light has a finite speed.
• Describe how the brightness of a light source is
  affected by distance.

3
Electromagnetic Waves
Section 1 Characteristics of Light
Chapter 13

• An electromagnetic wave is a wave that consists
  of oscillating electric and magnetic fields,
  which radiate outward from the source at the
  speed of light.
• Light is a form of electromagnetic radiation.
• The electromagnetic spectrum includes more than
  visible light.

4
The Electromagnetic Spectrum
Section 1 Characteristics of Light
Chapter 13
5
Electromagnetic Waves, continued
Section 1 Characteristics of Light
Chapter 13

• Electromagnetic waves vary depending on frequency
  and wavelength.
• All electromagnetic waves move at the speed of
  light. The speed of light, c, equals
• c 3.00 ? 108 m/s
• Wave Speed Equation
• c f?
• speed of light frequency ? wavelength

6
Electromagnetic Waves
Section 1 Characteristics of Light
Chapter 13
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7
Electromagnetic Waves, continued
Section 1 Characteristics of Light
Chapter 13

• Waves can be approximated as rays. This approach
  to analyzing waves is called Huygens principle.
• Lines drawn tangent to the crest (or trough) of a
  wave are called wave fronts.
• In the ray approximation, lines, called rays, are
  drawn perpendicular to the wave front.

8
Electromagnetic Waves, continued
Section 1 Characteristics of Light
Chapter 13

• Illuminance decreases as the square of the
  distance from the source.
• The rate at which light is emitted from a source
  is called the luminous flux and is measured in
  lumens (lm).

9
Chapter 13
Section 2 Flat Mirrors
Preview

• Objectives
• Reflection of Light
• Flat Mirrors

10
Objectives
Section 2 Flat Mirrors
Chapter 13

• Distinguish between specular and diffuse
  reflection of light.
• Apply the law of reflection for flat mirrors.
• Describe the nature of images formed by flat
  mirrors.

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Reflection of Light
Section 2 Flat Mirrors
Chapter 13

• Reflection is the change in direction of an
  electromagnetic wave at a surface that causes it
  tomove away from the surface.
• The texture of a surface affects how it reflects
  light.
• Diffuse reflection is reflection from a rough,
  texture surface such as paper or unpolished wood.
• Specular reflection is reflection from a smooth,
  shiny surface such as a mirror or a water surface.

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Reflection of Light, continued
Section 2 Flat Mirrors
Chapter 13

• The angle of incidence is the the angle between a
  ray that strikes a surface and the line
  perpendicular to that surface at the point of
  contact.
• The angle of reflection is the angle formed by
  the line perpendicular to a surface and the
  direction in which a reflected ray moves.
• The angle of incidence and the angle of
  reflection are always equal.

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Angle of Incidence and Angle of Reflection
Chapter 13
Section 2 Flat Mirrors
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14
Flat Mirrors
Section 2 Flat Mirrors
Chapter 13

• Flat mirrors form virtual images that are the
  same distance from the mirrors surface as the
  object is.
• The image formed by rays that appear to come from
  the image point behind the mirrorbut never
  really dois called a virtual image.
• A virtual image can never be displayed on a
  physical surface.

15
Image Formation by a Flat Mirror
Chapter 13
Section 2 Flat Mirrors
16
Comparing Real and Virtual Images
Chapter 13
Section 2 Flat Mirrors
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17
Chapter 13
Section 3 Curved Mirrors
Preview

• Objectives
• Concave Spherical Mirrors
• Sample Problem
• Parabolic Mirrors

18
Objectives
Section 3 Curved Mirrors
Chapter 13

• Calculate distances and focal lengths using the
  mirror equation for concave and convex spherical
  mirrors.
• Draw ray diagrams to find the image distance and
  magnification for concave and convex spherical
  mirrors.
• Distinguish between real and virtual images.
• Describe how parabolic mirrors differ
  fromspherical mirrors.

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Concave Spherical Mirrors
Section 3 Curved Mirrors
Chapter 13

• A concave spherical mirror is a mirror whose
  reflecting surface is a segment of the inside of
  a sphere.
• Concave mirrors can be used to form real images.
• A real image is an image formed when rays of
  light actually pass through a point on the image.
  Real images can be projected onto a screen.

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Image Formation by a Concave Spherical Mirror
Chapter 13
Section 3 Curved Mirrors
21
Concave Spherical Mirrors, continued
Section 3 Curved Mirrors
Chapter 13

• The Mirror Equation relates object distance (p),
  image distance (q), and focal length (f) of a
  spherical mirror.

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Concave Spherical Mirrors, continued
Section 3 Curved Mirrors
Chapter 13

• The Equation for Magnification relates image
  height or distance to object height or distance,
  respectively.

23
Rules for Drawing Reference Rays for Mirrors
Chapter 13
Section 3 Curved Mirrors
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24
Concave Spherical Mirrors, continued
Section 3 Curved Mirrors
Chapter 13

• Ray diagrams can be used for checking values
  calculated from the mirror and magnification
  equations for concave spherical mirrors.
• Concave mirrors can produce both real and virtual
  images.

25
Ray Tracing for a Concave Spherical Mirror
Chapter 13
Section 3 Curved Mirrors
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26
Sample Problem
Section 3 Curved Mirrors
Chapter 13

• Imaging with Concave Mirrors
• A concave spherical 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 to
  confirm your answer.

27
Sample Problem, continued
Section 3 Curved Mirrors
Chapter 13

• Imaging with Concave Mirrors
• Determine the sign and magnitude of the focal
  length and object size.
• f 10.0 cm p 30.0 cm
• The mirror is concave, so f is positive. The
  object is in front of the mirror, so p is
  positive.

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Sample Problem, continued
Section 3 Curved Mirrors
Chapter 13

• Imaging with Concave Mirrors
• 2. Draw a ray diagram using the rules for drawing
  reference rays.

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Sample Problem, continued
Section 3 Curved Mirrors
Chapter 13

• Imaging with Concave Mirrors
• 3. Use the mirror equation to relate the object
  and image distances to the focal length.

4. Use the magnification equation in terms of
object and image distances.
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Sample Problem, continued
Section 3 Curved Mirrors
Chapter 13

• 5. Rearrange the equation to isolate the image
  distance, and calculate. Subtract the reciprocal
  of the object distance from the reciprocal of the
  focal length to obtain an expression for the
  unknown image distance.

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Sample Problem, continued
Section 3 Curved Mirrors
Chapter 13

• Substitute the values for f and p into the
  mirror equation and the magnification equation to
  find the image distance and magnification.

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Sample Problem, continued
Section 3 Curved Mirrors
Chapter 13

• Evaluate your answer in terms of the image
  location and size.
• The image appears between the focal point (10.0
  cm) and the center of curvature (20.0 cm), as
  confirmed by the ray diagram. The image is
  smaller than the object and inverted (1 lt M lt
  0), as is also confirmed by the ray diagram. The
  image is therefore real.

33
Convex Spherical Mirrors
Section 3 Curved Mirrors
Chapter 13

• A convex spherical mirror is a mirror whose
  reflecting surface is outward-curved segment of a
  sphere.
• Light rays diverge upon reflection from a convex
  mirror, forming a virtual image that is always
  smaller than the object.

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Image Formation by a Convex Spherical Mirror
Chapter 13
Section 3 Curved Mirrors
35
Sample Problem
Section 3 Curved Mirrors
Chapter 13

• Convex Mirrors
• An upright pencil is placed in front of a convex
  spherical mirror with a focal length of 8.00 cm.
  An erect image 2.50 cm tall is formed 4.44 cm
  behind the mirror. Find the position of the
  object, the magnification of the image, and the
  height of the pencil.

36
Sample Problem, continued
Section 3 Curved Mirrors
Chapter 13

• Convex Mirrors
• Given
• Because the mirror is convex, the focal length
  is negative. The image is behind the mirror, so q
  is also negative.
• f 8.00 cm q 4.44 cm h 2.50 cm
• Unknown
• p ? h ?

37
Sample Problem, continued
Section 3 Curved Mirrors
Chapter 13

• Convex Mirrors
• Diagram

38
Sample Problem, continued
Section 3 Curved Mirrors
Chapter 13

• Convex Mirrors
• 2. Plan
• Choose an equation or situation Use the mirror
  equation and the magnification formula.

Rearrange the equation to isolate the unknown
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Sample Problem, continued
Section 3 Curved Mirrors
Chapter 13

• Convex Mirrors
• 3. Calculate
• Substitute the values into the equation and
  solve

40
Sample Problem, continued
Section 3 Curved Mirrors
Chapter 13

• Convex Mirrors
• 3. Calculate, continued
• Substitute the values for p and q to find the
  magnifi-cation of the image.

Substitute the values for p, q, and h to find
the height of the object.
41
Ray Tracing for a Convex Spherical Mirror
Chapter 13
Section 3 Curved Mirrors
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42
Parabolic Mirrors
Section 3 Curved Mirrors
Chapter 13

• Images created by spherical mirrors suffer from
  spherical aberration.
• Spherical aberration occurs when parallel rays
  far from the principal axis converge away from
  the mirrors focal point.
• Parabolic mirrors eliminate spherical aberration.
  All parallel rays converge at the focal point of
  aparabolic mirror.

43
Spherical Aberration and Parabolic Mirrors
Chapter 13
Section 3 Curved Mirrors
44
Reflecting Telescope
Chapter 13
Section 3 Curved Mirrors
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45
Chapter 13
Section 4 Color and Polarization
Preview

• Objectives
• Color
• Polarization of Light Waves

46
Objectives
Section 4 Color and Polarization
Chapter 13

• Recognize how additive colors affect the color of
  light.
• Recognize how pigments affect the color of
  reflected light.
• Explain how linearly polarized light is formed
  and detected.

47
Color
Section 4 Color and Polarization
Chapter 13

• Additive primary colors produce white light when
  combined.
• Light of different colors can be produced by
  adding light consisting of the primary additive
  colors (red, green, and blue).

48
Additive Color Mixing
Chapter 13
Section 4 Color and Polarization
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49
Color, continued
Section 4 Color and Polarization
Chapter 13

• Subtractive primary colors filter out all light
  when combined.
• Pigments can be produced by combining subtractive
  colors (magenta, yellow, and cyan).

50
Subtractive Color Mixing
Chapter 13
Section 4 Color and Polarization
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51
Polarization of Light Waves
Section 4 Color and Polarization
Chapter 13

• Linear polarization is the alignment of
  electro-magnetic waves in such a way that the
  vibrations of the electric fields in each of the
  waves are parallel to each other.
• Light can be linearly polarized through
  transmission.
• The line along which light is polarized is called
  the transmission axis of that substance.

52
Linearly Polarized Light
Chapter 13
Section 4 Color and Polarization
53
Aligned and Crossed Polarizing Filters
Chapter 13
Section 4 Color and Polarization
Crossed Filters
Aligned Filters
54
Polarization of Light Waves
Section 4 Color and Polarization
Chapter 13

• Light can be polarized by reflection and
  scattering.
• At a particular angle, reflected light is
  polarized horizontally.
• The sunlight scattered by air molecules is
  polarized for an observer on Earths surface.

55
Polarization by Reflection and Scattering
Chapter 13
Section 4 Color and Polarization
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