Light And Reflections


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Light And Reflections

  1. 1. Light and Reflections Students will be able to Compare different types of reflection Contrast different types of mirrors Understand index of reflection Contrast different types of lenses Page 113
  2. 2. Reflections 114
  3. 3. Reflection of Light Rays <ul><li>Ray – Straight line wave to represent light </li></ul>114
  4. 4. Reflection of Light Rays <ul><li>Two types of Reflection </li></ul><ul><li>Regular </li></ul><ul><li>Light hits a smooth surface </li></ul><ul><li>All rays reflected at same angle </li></ul><ul><li>Sharp image </li></ul><ul><li>Diffuse </li></ul><ul><li>Uneven surface </li></ul><ul><li>Each ray reflects differently </li></ul>114
  5. 5. Two Types 114
  6. 6. Plane Mirrors <ul><li>Flat sheet of glass with a smooth silver coating </li></ul><ul><li>What you see in mirror is virtual image </li></ul><ul><li>Appears to be behind the mirror </li></ul><ul><li>Same size and upright </li></ul><ul><li>Right and left sides are reversed </li></ul>115
  7. 7. Plane Mirror 115
  8. 8. Concave Mirrors <ul><li>A mirror with a surface that curves inward like a bowl </li></ul><ul><li>Optical axis =Imaginary line that cut mirror in half </li></ul><ul><li>Focal point = Point where rays meet </li></ul><ul><li>The more curved then the closer the focal point </li></ul>116
  9. 9. Concave Mirrors 116
  10. 10. Concave Mirrors 116
  11. 11. Concave Mirrors <ul><li>Real image is produced when rays meet </li></ul><ul><li>Always upside down </li></ul><ul><li>Can be larger or smaller </li></ul><ul><li>Virtual image if inside focal point </li></ul><ul><li>Always right side up </li></ul><ul><li>Always larger </li></ul>117
  12. 12. Concave Mirrors 117
  13. 13. Convex Mirrors <ul><li>Mirror curves outward </li></ul><ul><li>Always virtual image </li></ul><ul><li>Always smaller </li></ul><ul><li>Used in side mirrors of cars </li></ul><ul><li>Picture large world in small mirror </li></ul><ul><li>Problem is that everything is small </li></ul>118
  14. 14. Convex Mirrors 118
  15. 15. Refraction <ul><li>Light waves bend when they enter a new medium at an angle </li></ul>120
  16. 16. Index of Refraction <ul><li>Measure of how much light bends </li></ul><ul><li>The higher the number the more it bends light </li></ul>120
  17. 17. Prisms and Rainbows <ul><li>Longer wavelength bends least (red on top) </li></ul><ul><li>Short wavelength bends more (violet on bottom) </li></ul>121
  18. 18. Mirages <ul><li>Temperature changes will cause light to change speed (light wave moves faster in when hot) </li></ul>121
  19. 19. Lenses <ul><li>Lens = Curved piece of glass to refract light </li></ul>122
  20. 20. Convex Lens <ul><li>Thicker in the center than the edges </li></ul><ul><li>Can produce virtual or real images depending on location </li></ul>122
  21. 21. Convex Lens 122
  22. 22. Concave Lens <ul><li>Thicker on the edges than in the middle </li></ul><ul><li>Only virtual images </li></ul>122
  23. 23. Quiz
  24. 24. Homework <ul><li>Describe one type of mirrors and one type of lens </li></ul>