Refraction

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Refraction

• Chapter 15

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Refraction

• Refraction The bending of light as it travels
  from one medium to another
• Refraction occurs when lights velocity changes
• The speed of light varies with the medium

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Refraction
Ti Angle of Incidence
Tr Angle of Refraction
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Index of Refraction

• Index of Refraction speed of light in vacuum
• 
  speed of light in medium

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Only valid for light with wavelength of 589 nm
in a vacuum (p. 564)
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Snells Law

• Snells Law determines the angle of refraction
• nisin(?i) nrsin(?r)
• ni Index of refraction of first medium
• nr Index of refraction of second medium
• ?i Angle of Incidence
• ?r Angle of Refraction

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Bending relative to the normal

• When light passes from a medium with a low index
  of refraction to a medium with a high index of
  refraction, the ray bends toward the normal
• When light passes from a medium with a high index
  of refraction to a medium with a low index of
  refraction, the ray bends away from the normal

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CATBEAR trying to catch a fish!!!
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Sample Problem (p.567 4)

• Sunlight passes into a raindrop at an angle of
  22.5 from the normal at one point on the
  droplet. What is the angle of refraction?

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Sunlight into a raindrop

• Will the ray bend away from the normal or towards
  the normal?
• Low n to high n, the ray will bend toward the
  normal

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Use Snells Law