Reflection and Refraction

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Reflection and Refraction

• Pg. 57

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Reflection of light

• Can be modeled as a light ray
• We can trace the path of light in ray diagrams
• Angle of reflectionangle of incidence
• i r
• This equality is called the law of reflection

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Calculating angle of reflection

• The angle of incidence and the angle of
  reflection are measured from a line that is
  perpendicular to the surface.
• This line is called the normal.

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Measuring the angle of reflection

1. Draw the normal by placing your protractor on the
   point where the light ray hits the surface.
2. Measure the angle of incidence
3. Draw a line equal to the angle of incidence going
   the opposite direction.

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Mirrors

• Mirrors form virtual images.
• Curved mirrors distort images.
• Mirrors that bulge are called convex mirrors.
• Convex mirrors -make images appear smaller than
  they actually are.
• Indented mirrors are called concave mirrors.
• Concave mirrors magnify objects.

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Colors

• An objects color is the color that is reflected.
• The wavelength of the color is reflected into
  your eyes while the other colors are absorbed by
  the object.
• Mixing light of the 3 primary colors (red, green,
  and blue) creates white light.
• Secondary colors are made by mixing two primary
  colors.
• If the three primary colors are combined, all
  visible light is absorbed so you see black.
• Black is not a color, it is the absence of color.

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Refraction of light

• Refraction makes objects appear to be in a
  different position
• The angle of refraction can be calculated
• The angle of refraction is also called the index
  of refraction

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Measuring the angle of refraction

1. Draw the normal line perpendicular to the point
   where the light ray hits the surface.
2. Connect the two lines
3. Measure the angle of incidence
4. Measure the angle of refraction (angle between
   the normal and drawn line)

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Measuring the angle of refraction
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Lenses

• Lens-a transparent object that refracts light
  waves so they converge or diverge.
• Converging lens bends inward.
• Diverging lens bends outward.
• Lenses magnify objects.

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Lenses for magnification

• Magnification is any change in the size of an
  image compared to the object.
• The focal point of a light ray is made when you
  can focus light rays into a small area.

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The eye

• The eye uses refraction of light to see.
• Light enters the cornea. It then passes through
  the pupil. The light then reaches the lens where
  it can be curved to focus an image on the retina.
  
• The retina is composed of rods and cones. The
  cones are responsible for color vision.

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Dispersion and prisms

• Prism-a transparent solid that consists of two
  planes that are at an angle with each other.
• Dispersion-when light separates into different
  colors because of differences in wave speed.
• Rainbows are caused by dispersion.