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Preview Objectives Electromagnetic Waves Chapter 13 Section 1 Characteristics of Light.

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Presentation on theme: "Preview Objectives Electromagnetic Waves Chapter 13 Section 1 Characteristics of Light."— Presentation transcript:

1 Preview Objectives Electromagnetic Waves Chapter 13 Section 1 Characteristics of Light

2 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.

3 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.

4 Chapter 13 The Electromagnetic Spectrum Section 1 Characteristics of Light

5 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  10 8 m/s Wave Speed Equation c = f speed of light = frequency  wavelength

6 Click below to watch the Visual Concept. Visual Concept Chapter 13 Section 1 Characteristics of Light Electromagnetic Waves

7 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.

8 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).

9 Chapter 13 Assignments Page 449 Practice A 1,2(2), 3(2)

10 Preview Objectives Reflection of Light Flat Mirrors Chapter 13 Section 2 Flat Mirrors

11 Chapter 13 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.

12 Section 2 Flat Mirrors Chapter 13 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. –Regular reflection is reflection from a smooth, shiny surface such as a mirror or a water surface.

13 Section 2 Flat Mirrors Chapter 13 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.

14 Click below to watch the Visual Concept. Visual Concept Chapter 13 Section 2 Flat Mirrors Angle of Incidence and Angle of Reflection

15 Section 2 Flat Mirrors Chapter 13 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.

16 Chapter 13 Image Formation by a Flat Mirror Section 2 Flat Mirrors

17 Click below to watch the Visual Concept. Visual Concept Chapter 13 Section 2 Flat Mirrors Comparing Real and Virtual Images

18 Chapter 13 Assignments Page 449 Practice A 1,2(2), 3(2) P454 Section Review #2 How tall would a mirror have to be for a 6ft tall person to see their entire body?

19 6ft tall person, mirror? mirror person

20 Preview Objectives Concave Spherical Mirrors Sample Problem Parabolic Mirrors Chapter 13 Section 3 Curved Mirrors

21 Chapter 13 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.

22 Section 3 Curved Mirrors Chapter 13 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.

23 Images Real – light rays actually pass through the point where the image is formed. Virtual – light rays appear to pass through the point where the image is formed but actually do not. Upright – Inverted Reversed Enlarged-Reduced

24 Mirrors Flat or Plain Concave Convex

25 Curved Mirrors Focal point – the point where parallel incident rays converge when they are reflected. –For a concave mirror, the focal point is on the same side as the source of light rays. – For a convex mirror the focal point is behind the mirror from the source of the light rays. Center of curvature- the center of the circle from which the mirror is made. Focal length is ½ the radius of curvature. –Focal point is ½ way between center of curvature and the mirror.

26 Concave Mirror Image

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

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

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

30 Click below to watch the Visual Concept. Visual Concept Chapter 13 Section 3 Curved Mirrors Rules for Drawing Reference Rays for Mirrors

31 3 Rays (any 2) A ray passing through the focal point will be reflected parallel to the axis of the mirror. A ray parallel to the axis will be reflected through the focal point. A ray passing through the center of curvature of a mirror will be reflected back on itself.

32 Convex Mirror Image

33 Section 3 Curved Mirrors Chapter 13 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.

34 Click below to watch the Visual Concept. Visual Concept Chapter 13 Section 3 Curved Mirrors Ray Tracing for a Concave Spherical Mirror Replay

35 Section 3 Curved Mirrors Chapter 13 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.

36 Chapter 13 Assignments Page 449 Practice A 1,2(2), 3(2) P454 Section Review #2 Page 462 Practice B 1(5), 2(5) (4for answer+1 for rays)

37 Section 3 Curved Mirrors Chapter 13 Sample Problem, continued Imaging with Concave Mirrors 1.Determine the sign and magnitude of the focal length and object distance. f = cmp = cm The mirror is concave, so f is positive. The object is in front of the mirror, so p is positive.

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

39 Section 3 Curved Mirrors Chapter 13 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.

40 Section 3 Curved Mirrors Chapter 13 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.

41 Section 3 Curved Mirrors Chapter 13 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.

42 Section 3 Curved Mirrors Chapter 13 Sample Problem, continued 6.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.

43 Section 3 Curved Mirrors Chapter 13 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.

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

45 Chapter 13 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.

46 Section 3 Curved Mirrors Chapter 13 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 = ?

47 Chapter 13 Assignments Page 449 Practice A 1,2(2), 3(2) P454 Section Review #2 Page 462 Practice B 1(5), 2(5) (4for answer+1 for rays) Page 466 Practice C 3(5), 5(3), 6(4) Page 477 Chapter Review 20(2), 34(6),36(3)

48 3 Rays (any 2) A ray passing through the focal point will be reflected parallel to the axis of the mirror. A ray parallel to the axis will be reflected through the focal point. A ray passing through the center of curvature of a mirror will be reflected back on itself.

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

50 Section 3 Curved Mirrors Chapter 13 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:

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

52 Section 3 Curved Mirrors Chapter 13 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.

53 Click below to watch the Visual Concept. Visual Concept Chapter 13 Section 3 Curved Mirrors Ray Tracing for a Convex Spherical Mirror

54 Section 3 Curved Mirrors Chapter 13 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.

55 Chapter 13 Spherical Aberration and Parabolic Mirrors Section 3 Curved Mirrors

56 Click below to watch the Visual Concept. Visual Concept Chapter 13 Section 3 Curved Mirrors Reflecting Telescope

57 Preview Objectives Color Polarization of Light Waves Chapter 13 Section 4 Color and Polarization

58 Chapter 13 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.

59 Section 4 Color and Polarization Chapter 13 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).

60 Click below to watch the Visual Concept. Visual Concept Chapter 13 Section 4 Color and Polarization Additive Color Mixing

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

62 Click below to watch the Visual Concept. Visual Concept Chapter 13 Section 4 Color and Polarization Subtractive Color Mixing

63 Section 4 Color and Polarization Chapter 13 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.

64 Chapter 13 Linearly Polarized Light Section 4 Color and Polarization

65 Chapter 13 Aligned and Crossed Polarizing Filters Section 4 Color and Polarization Crossed FiltersAligned Filters

66 Section 4 Color and Polarization Chapter 13 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.

67 Click below to watch the Visual Concept. Visual Concept Chapter 13 Section 4 Color and Polarization Polarization by Reflection and Scattering


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