Reflection

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Reflection
Law of Reflection Incoming Angle Reflected
Angle
Light Beam
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Ooh, Shiny
Why smooth surfaces are shiny from one angle and
darker from all other angles?
A smooth surface reflects all of the incoming
sunlight in the same direction, so one preferred
angle gets most of the light.
A rough surface reflects the incoming sunlight in
many directions, so the light is randomly
scattered.
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Refraction
Law of Refraction (Snells Law) n1 sin ?1 n2
sin ?2
Incoming Beam
?1
?2
sin is the trig function sine, it takes an angle
an spits out a numerical value. How and why does
not concern us now.
Refracted Beam
Air/Glass Interface
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Refraction The Lifeguard Analogy
Lifeguard needs to reach drowning man as quickly
as possible. The shortest distance between the
lifeguard and the drowning man is a straight
line. Yet, since the lifeguard can run much
faster than she can swim, the lifeguard will
reach the drowning man faster if she decreases
the distance she has to swim by running a greater
distance. Even though the total distance is
greater, the lifeguards faster running speed
will make this the fastest option.
Lifeguard Post
Shortest Distance
?1
?2
Index of refraction becomes ratio of sprinting
speed to speed of either running on sand or
swimming in ocean
Drowning Man
Beach / Ocean Interface
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Refraction
Incoming Beam
Refracted Beam
Doubly Refracted Beam
Glass / Air Interface
Air / Glass Interface
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Refraction
Incoming Beam of White Light
Doubly Refracted Beams
Glass / Air Interface
Air / Glass Interface
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Air / Glass Interface
Glass / Air Interface
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Air / Glass Interface
Glass / Air Interface
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Air / Glass Interface
Glass / Air Interface
Air / Glass Interface
Glass / Air Interface
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Focal Point
Convex Lens
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Light Source at Focal Point
Convex Lens
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Light Gathering
Object
Focal Point
Focal Point
Image
Convex Lens
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Focal Point
Convex Lens
Focal Point
Convex Lens
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Focal Point
Convex Lens
Focal Point
Convex Lens
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