Chapter 17: Light through multiple reflections

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Chapter 17 Lightthrough multiple reflections

• Kelly Lines
• Nicole McCown
• Charlie Rogers
• Kattie Piazza

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Shadows Summary

• We know that light travels in straight lines
  because of the shadows produced.
• Umbrathe darkest region where all the shadows
  overlap
• Penumbrasurrounding the umbra, where only some
  of the individual shadows overlap.

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Pinhole Cameras Summary

• Light that strikes most objects leaves in
  different directions so by controlling the light
  rays that hit the object we can create an image.
• Reducing the size of the pinhole produces a
  sharper but dimmer image because there is less
  light entering through the pinhole.

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Conceptual Question 11

• What affect does enlarging the hole in the
  pinhole camera have on the image?

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Answer

• Because more light enters the larger pinhole, the
  image will be brighter and fuzzier.

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Reflections Summary

• We see most objects because they reflect some of
  the light that hits them.
• Diffuse reflection reflection of rays from a
  rough surface, the reflected rays dont leave at
  fixed angles
• Law of Reflection the angle of reflection is
  equal to the angle of incidence
• Normal a line perpendicular to a surface or curve

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Flat Mirrors Summary

• Mirrors produce real and virtual images.
• Light converges to form real images that can be
  projected, where as light only appears to come
  from virtual images.
• The virtual image formed by a flat mirror is
  located on a normal to the mirror at the same
  distance behind the mirror as the object is in
  front of the mirror.
• The sizes of the image and the object are the
  SAME ?

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Multiple Reflections Summary

• When two mirrors are directly opposite of each
  other, you get an infinite number of images, with
  successive images being farther and farther away
  from the object.

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OopsMisunderstandings ?

• People often think that when they move their head
  the image also moves however, the image DOES NOT
  move because the image is behind the mirror
  instead of on the mirrors surface.
• REMINDER The image in pinhole cameras is
  inverted! ? ? ? ? ? ?

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Exercise 1

• A 4cm diameter ball is located 40 cm from a point
  source of light and 80 cm from a wall. What is
  the size of the shadow on the wall?

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Answer

• Charlie will show you on the board !!!!
• ARE YOU READY ????