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Eye and Light

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Eyeball, Light, waves, electromagnetic spectrum,

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Eye and Light

  1. 1. Chapter Menu Lesson 1: What is light? Lesson 2: Light and Matter Lesson 3: Using Lenses Lesson 4: The Eye and Vision Click on a hyperlink to view the corresponding lesson.
  2. 2. wavelength frequency medium electromagnetic spectrum 11.1 What is light?
  3. 3. Light Transfers Energy • Similar to water waves, light waves also carry energy from place to place. 11.1 What is light?
  4. 4. Parts of a Wave • The distance between any two crests of any two troughs is the wavelength. 11.1 What is light?
  5. 5. Frequency and Wavelength • The frequency of a wave is the number of wavelengths that pass a given point in one second. 11.1 What is light? • As the frequency of a wave increases, wavelength decreases.
  6. 6. Electromagnetic Waves • The substance through which a wave moves is called the medium. 11.1 What is light? • Light is an electromagnetic wave, which is a type of wave that can travel in empty space as well as in matter.
  7. 7. A Range of Wavelengths • The electromagnetic spectrum includes all electromagnetic waves. 11.1 What is light? • It is arranged in order, from those with the longest wavelengths to those with the shortest wavelengths. • Frequency increases as wavelength decreases, and is arranged in order of increasing frequency.
  8. 8. Visible Light • The visible light spectrum is the range of electromagnetic waves human eyes can detect. 11.1 What is light? • Visible light wavelengths are measured in nanometers (nm). • The wavelengths range from 700 nm to 400 nm.
  9. 9. 11.1 What is light?
  10. 10. What is the amplitude of a wave? A distance from crest to crest B distance from crest to trough C distance from crest to resting position D wavelength x frequency 11.1 What is light? A B C D 0% 0%0%0% 1. A 2. B 3. C 4. D
  11. 11. What is a wavelength? A the distance from crest to trough B the distance from crest to the rest position C the distance from crest to crest D the opposite of frequency 11.1 What is light? A B C D 0% 0%0%0% 1. A 2. B 3. C 4. D
  12. 12. What is the term for the substance through which a wave moves? A medium B substrate C water D vacuum 11.1 What is light? A B C D 0% 0%0%0% 1. A 2. B 3. C 4. D
  13. 13. End of lesson
  14. 14. absorption transmission scattering refraction law of reflection 11.2 Light and Matter
  15. 15. The Interaction of Light and Matter • All electromagnetic waves, including light, transfer energy from one place to another. • When light rays hit matter, they can be absorbed, reflected, or pass through the matter. 11.2 Light and Matter
  16. 16. Absorption of Light • The transfer of energy can cause the temperature of the material to increase. • Absorption occurs when light rays hit a material, and some of the rays’ energy is transferred to the atoms in the material. 11.2 Light and Matter
  17. 17. Transmission of Light • Whether the light waves are transmitted or absorbed depends on the wavelength of the light waves. • Transmission occurs when light waves strike a material and pass through it, such as with glass. 11.2 Light and Matter
  18. 18. Scattering of Light • Scattering occurs when a material causes light waves traveling in one direction to travel in all directions. 11.2 Light and Matter
  19. 19. Opaque, Transparent, and Translucent Materials 11.2 Light and Matter • The three candleholders are made of different materials that absorb, transmit, and scatter light in different ways.
  20. 20. The Speed of Light in Different Materials 11.2 Light and Matter • No object or wave can move faster than the speed of light in empty space. • When light waves travel in matter, they move more slowly.
  21. 21. Refraction • Refraction occurs when a light ray changes direction when it moves from one material to another. 11.2 Light and Matter
  22. 22. Refraction and Speed Changes • Light waves change direction— refract—when they change speed moving from one medium to another. 11.2 Light and Matter Bending Light
  23. 23. The Visible Spectrum • White light is a combination of all light waves in the visible light spectrum. 11.2 Light and Matter • Almost any color of light can be made by mixing the three primary colors—red, green, and blue—in different amounts.
  24. 24. Reflection • According to the law of reflection, when a light ray is reflected from a surface, the angle of incidence equals the angle of reflection. 11.2 Light and Matter
  25. 25. Regular and Diffuse Reflection • Light ray reflected from an uneven surface hits a spot in the surface that is at a slightly different angle, causing the rays to go in many different directions. • Diffuse reflection is the reflection of light rays from a rough surface. 11.2 Light and Matter
  26. 26. Regular and Diffuse Reflection (cont.) • The smooth surface of a mirror reflects parallel light rays so that they remain parallel. • This is called regular reflection. 11.2 Light and Matter
  27. 27. Reflection and Color • As white light strikes and object, some of the light is absorbed and some is reflected. • The reflected light enters your eyes and causes you to see the object. 11.2 Light and Matter Color
  28. 28. What is the term for the process of transferring light energy to the molecules in a material? A transmission B absorption C scattering D refraction 11.2 Light and Matter A B C D 0% 0%0%0% 1. A 2. B 3. C 4. D
  29. 29. Which of the following does light travel fastest through? A transparent objects B empty space C air D water 11.2 Light and Matter A B C D 0% 0%0%0% 1. A 2. B 3. C 4. D
  30. 30. Why does an object appear to be blue? A it absorbs the blue wavelength B it scatters the blue wavelength C it reflects all the other colors except blue D it absorbs all the wavelengths except blue 11.2 Light and Matter A B C D 0% 0%0%0% 1. A 2. B 3. C 4. D
  31. 31. End of lesson
  32. 32. 11.3 Using Lenses lens convex lens focal point focal length
  33. 33. What is a convex lens? • A lens is a transparent object with at least one curved side that causes light waves to bend. • A convex lens is a lens that bulges outward. 11.3 Using Lenses – Convex lens: parallel light rays are bent so they come together, or converge – Concave lens: parallel light rays spread apart, or diverge
  34. 34. What is a convex lens? (cont.) • A concave lens is thinner in the middle than at the edges. 11.3 Using Lenses
  35. 35. Light’s Path Through a Convex Lens • A light ray bends when it slows down moving from air into the lens. • The light ray bends again when it speeds up moving from the lens back into the air. 11.3 Using Lenses
  36. 36. Focal Point and Focal Length • The focal point is the point where all of the beams of light converge. • In a convex lens, all light rays traveling parallel to the optical axis are bent so that they pass through the focal point. 11.3 Using Lenses
  37. 37. Focal Point and Focal Length (cont.) • The focal length is the distance from the center of the lens to the focal points. 11.3 Using Lenses
  38. 38. Image Formation by a Convex Lens • The image formed by a convex lens depends on the position of an object relative to the focal point. 11.3 Using Lenses
  39. 39. Optical Instruments • An optical instrument uses lenses to focus light and create useful images. 11.3 Using Lenses • Different optical instruments do this by combining lenses in various ways. • Types of optical instruments – Cameras – Telescopes – Microscopes
  40. 40. Cameras • A camera is focused by moving various lenses back and forth until a sharp image is formed. 11.3 Using Lenses • The image is smaller than the object and is upside down. • To take a picture, the shutter opens so that light enters the camera, and film or an electronic sensor is exposed.
  41. 41. Cameras (cont.) • To control the amount of light that reaches the film or light sensor, cameras have a diaphragm or an aperture. 11.3 Using Lenses
  42. 42. Telescopes • As an object gets farther away, less of the light from the object enters the openings in your eyes. 11.3 Using Lenses • A telescope is an optical instrument that makes far-away objects seem closer. • There are two basic types of telescopes— refracting and reflecting.
  43. 43. Refracting Telescopes • The objective lens in a refracting telescope is much larger than the opening in a human eye. 11.3 Using Lenses • Much more light from a distant object enters the objective lens than would enter an eye.
  44. 44. Reflecting Telescopes • An image of a distant object is formed inside the telescope tube when light rays are reflected from the curved surface of a mirror. 11.3 Using Lenses • The largest telescopes are reflecting telescopes.
  45. 45. Microscopes • The eyepiece lens of a microscope is positioned so it is closer to the image than one focal length. 11.3 Using Lenses • This makes the image enlarged by the objective lens even larger.
  46. 46. Where do all the beams of light passing through a convex lens converge? A focal point B optical axis C two focal lengths from the lens D in the center of the lens 11.3 Using Lenses A B C D 0% 0%0%0% 1. A 2. B 3. C 4. D
  47. 47. What happens to light when it moves from air into a convex lens? A it is reflected B it is scattered C it slows down D it speeds up 11.3 Using Lenses A B C D 0% 0%0%0% 1. A 2. B 3. C 4. D
  48. 48. Which uses a curved mirror to form an image that is magnified by an eyepiece lens? A refracting telescope B reflecting telescope C camera D microscope 11.3 Using Lenses A B C D 0% 0%0%0% 1. A 2. B 3. C 4. D
  49. 49. End of lesson
  50. 50. 11.4 The Eye and Vision cornea pupil iris retina pigment
  51. 51. How the Eye Forms an Image • As light enters your eye, lenses in your eye focus light to produce an image on the back of your eye. • Special cells at the back of the eye convert the image into electrical signals that travel to your brain. 11.4 The Eye and Vision
  52. 52. Cornea • Light enters your eye through the cornea, which is a clear area of the sclera—the outer layer of the eye. 11.4 The Eye and Vision The Eye
  53. 53. 11.4 The Eye and Vision Parts of the Eye
  54. 54. Iris • The pupil is the dark opening into the interior of your eye. 11.4 The Eye and Vision • The pupil is surrounded by the iris—the colored part of your eye behind the cornea.
  55. 55. Lens • The lens of your eye is convex and flexible. 11.4 The Eye and Vision • The ciliary muscles attached to the lens change its shape depending on the distance of the object being looked at.
  56. 56. Retina • The retina is a sheet of light-sensitive cells in the back of the eye. 11.4 The Eye and Vision • Rod cells respond to dim light and cone cells enable you to see colors.
  57. 57. Seeing Color • The response of cone cells to different wavelengths of light cause you to see objects as having color. 11.4 The Eye and Vision • Three types of cone cells: – One responds to the wavelengths of red and yellow light, causing you to see red. – One responds to yellow and green light, causing you to see green. – One responds to blue and violet light, causing you to see blue.
  58. 58. Pigment Colors • A pigment is a material used to change the color of other materials or objects. • The color of a pigment depends on the wavelengths of the light it reflects. 11.4 The Eye and Vision
  59. 59. Pigment Colors (cont.) 11.4 The Eye and Vision Reflecting Light
  60. 60. Color Printing • The pictures in magazines are formed by many tiny dots of color. • Usually, the primary colors of pigments, as well as black, are used. 11.4 The Eye and Vision
  61. 61. Common Vision Problems • Color deficiency: either lack red or green cones, or the cones do not function correctly 11.4 The Eye and Vision
  62. 62. Common Vision Problems (cont.) • Nearsightedness: cannot see faraway objects clearly 11.4 The Eye and Vision
  63. 63. Common Vision Problems (cont.) • Farsightedness: cannot see nearby objects clearly 11.4 The Eye and Vision How are lenses used to correct vision?
  64. 64. What controls the amount of light that enters your eye? A ciliary muscles B cornea C sclera D iris 11.4 The Eye and Vision A B C D 0% 0%0%0% 1. A 2. B 3. C 4. D
  65. 65. What part of the eye enables you to see colors? A pupil B rod cells C cone cells D optic nerve 11.4 The Eye and Vision A B C D 0% 0%0%0% 1. A 2. B 3. C 4. D
  66. 66. Which describes a nearsighted eye? A it is missing some cone cells or the cones don’t function properly B the eyeball is too short for the lens to form a clear image C the rods at the back of the eye do not function properly D the eyeball is too long for the lens to form a clear image 11.4 The Eye and Vision A B C D 0% 0%0%0% 1. A 2. B 3. C 4. D
  67. 67. End of lesson – next slide is the chapter assessment
  68. 68. What is the wavelength range of visible light? A 700–400 nm B 200–600 nm C 300–900 nm D 800–300 nm A B C D 0% 0%0%0% 1. A 2. B 3. C 4. D
  69. 69. What occurs when light waves strike a material and pass through it? A reflection B absorption C transmission D scattering A B C D 0% 0%0%0% 1. A 2. B 3. C 4. D
  70. 70. Which is true according to the law of reflection? A if light is not refracted, it is reflected B parallel rays of light remain parallel when they are reflected C the angle of incidence equals the angle of reflection D the angle of reflection is twice the angle of incidenceA B C D 0% 0%0%0% 1. A 2. B 3. C 4. D
  71. 71. Which describes the image formed by an object more than two focal lengths from a convex lens? A upside down and larger than the object B upside down and smaller than the object C right side up and smaller than the object D right side up and larger than the object A B C D 0% 0%0%0% 1. A 2. B 3. C 4. D
  72. 72. Which part of the eye contains light- sensitive rods and cones? A sclera B cornea C optic nerve D retina A B C D 0% 0%0%0% 1. A 2. B 3. C 4. D
  73. 73. What property of a wave increases as wavelength decreases? A crest B trough C frequency D amplitude SCI 6.a A B C D 0% 0%0%0% 1. A 2. B 3. C 4. D
  74. 74. In which order does light pass through the parts of the eye? A lens, retina, pupil B lens, pupil, retina C retina, lens, pupil D pupil, lens, retina SCI 6.b A B C D 0% 0%0%0% 1. A 2. B 3. C 4. D
  75. 75. Which light waves are refracted the least after passing through a prism? A red B violet C yellow D blue SCI 6.c A B C D 0% 0%0%0% 1. A 2. B 3. C 4. D
  76. 76. What occurs when you look at an object at the bottom of a pool of water? A reflection B refraction C absorption D scattering SCI 6.f A B C D 0% 0%0%0% 1. A 2. B 3. C 4. D
  77. 77. What type of lens is present in both your eye and a microscope? A objective B eyepiece C convex D concave SCI 6.d A B C D 0% 0%0%0% 1. A 2. B 3. C 4. D

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