1. Section 1 Characteristics of Light
Chapter 13
Objectives
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.

2. Electromagnetic Waves
Section 1 Characteristics of Light
Chapter 13
Electromagnetic Waves
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.

3. The Electromagnetic Spectrum
Section 1 Characteristics of Light
Chapter 13
The Electromagnetic Spectrum

4. Electromagnetic Waves, continued
Section 1 Characteristics of Light
Chapter 13
Electromagnetic Waves, continued
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

5. Electromagnetic Waves, continued
Section 1 Characteristics of Light
Chapter 13
Electromagnetic Waves, continued
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.

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

7. Chapter 13
Section 2 Flat Mirrors
Objectives
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.

8. Chapter 13 Reflection of Light
Section 2 Flat Mirrors
Reflection of Light
Reflection is the change in direction of an electromagnetic wave at a surface that causes it to move 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.

9. Reflection of Light, continued
Chapter 13
Section 2 Flat Mirrors
Reflection of Light, continued
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.

10. Chapter 13
Section 2 Flat Mirrors
Flat Mirrors
Flat mirrors form virtual images that are the same distance from the mirror’s surface as the object is.
The image formed by rays that appear to come from the image point behind the mirror—but never really do—is called a virtual image.
A virtual image can never be displayed on a physical surface.

11. Image Formation by a Flat Mirror
Chapter 13
Section 2 Flat Mirrors
Image Formation by a Flat Mirror

12. Chapter 13
Section 3 Curved Mirrors
Objectives
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 from spherical mirrors.

13. Concave Spherical Mirrors
Chapter 13
Section 3 Curved Mirrors
Concave Spherical Mirrors
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.

14. Image Formation by a Concave Spherical Mirror
Chapter 13
Section 3 Curved Mirrors
Image Formation by a Concave Spherical Mirror

15. Concave Spherical Mirrors, continued
Chapter 13
Section 3 Curved Mirrors
Concave Spherical Mirrors, continued
The Mirror Equation relates object distance (p), image distance (q), and focal length (f) of a spherical mirror.

16. Concave Spherical Mirrors, continued
Chapter 13
Section 3 Curved Mirrors
Concave Spherical Mirrors, continued
The Equation for Magnification relates image height or distance to object height or distance, respectively.

17. Concave Spherical Mirrors, continued
Chapter 13
Section 3 Curved Mirrors
Concave Spherical Mirrors, continued
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.

18. Chapter 13 Sample Problem Imaging with Concave Mirrors
Section 3 Curved Mirrors
Sample Problem
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.

19. Sample Problem, continued
Chapter 13
Section 3 Curved Mirrors
Sample Problem, continued
Imaging with Concave Mirrors
Determine the sign and magnitude of the focal length and object size.
f = cm p = cm
The mirror is concave, so f is positive. The object is in front of the mirror, so p is positive.

20. Sample Problem, continued
Chapter 13
Section 3 Curved Mirrors
Sample Problem, continued
Imaging with Concave Mirrors
2. Draw a ray diagram using the rules for drawing reference rays.

21. Sample Problem, continued
Chapter 13
Section 3 Curved Mirrors
Sample Problem, continued
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.

22. Sample Problem, continued
Chapter 13
Section 3 Curved Mirrors
Sample Problem, continued
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.

23. Sample Problem, continued
Chapter 13
Section 3 Curved Mirrors
Sample Problem, continued
Substitute the values for f and p into the mirror equation and the magnification equation to find the image distance and magnification.

24. Sample Problem, continued
Chapter 13
Section 3 Curved Mirrors
Sample Problem, continued
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 < M < 0), as is also confirmed by the ray diagram. The image is therefore real.

25. Convex Spherical Mirrors
Chapter 13
Section 3 Curved Mirrors
Convex Spherical Mirrors
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.

26. Image Formation by a Convex Spherical Mirror
Chapter 13
Section 3 Curved Mirrors
Image Formation by a Convex Spherical Mirror

27. Chapter 13 Sample Problem Convex Mirrors
Section 3 Curved Mirrors
Sample Problem
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.

28. Sample Problem, continued
Chapter 13
Section 3 Curved Mirrors
Sample Problem, continued
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 = ?

29. Sample Problem, continued
Chapter 13
Section 3 Curved Mirrors
Sample Problem, continued
Convex Mirrors
Diagram:

30. Sample Problem, continued
Chapter 13
Section 3 Curved Mirrors
Sample Problem, continued
Convex Mirrors
2. Plan
Choose an equation or situation: Use the mirror equation and the magnification formula.
Rearrange the equation to isolate the unknown:

31. Sample Problem, continued
Chapter 13
Section 3 Curved Mirrors
Sample Problem, continued
Convex Mirrors
3. Calculate
Substitute the values into the equation and solve:

32. Sample Problem, continued
Chapter 13
Section 3 Curved Mirrors
Sample Problem, continued
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.

33. Chapter 13 Parabolic Mirrors
Section 3 Curved Mirrors
Parabolic Mirrors
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 a parabolic mirror.

34. Spherical Aberration and Parabolic Mirrors
Chapter 13
Section 3 Curved Mirrors
Spherical Aberration and Parabolic Mirrors

35. Chapter 13
Section 4 Color and Polarization
Objectives
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.

36. Chapter 13
Section 4 Color and Polarization
Color
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).

37. Chapter 13 Color, continued
Section 4 Color and Polarization
Color, continued
Subtractive primary colors filter out all light when combined.
Pigments can be produced by combining subtractive colors (magenta, yellow, and cyan).

38. Polarization of Light Waves
Chapter 13
Section 4 Color and Polarization
Polarization of Light Waves
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.

39. Linearly Polarized Light
Chapter 13
Section 4 Color and Polarization
Linearly Polarized Light

40. Aligned and Crossed Polarizing Filters
Chapter 13
Section 4 Color and Polarization
Aligned and Crossed Polarizing Filters
Aligned Filters
Crossed Filters

41. Polarization of Light Waves
Chapter 13
Section 4 Color and Polarization
Polarization of Light Waves
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 Earth’s surface.