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Published byClyde Oliver Modified over 8 years ago
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-Atmospheric Refraction -Total Internal Reflection
-Prisms and Rainbows -Total Internal Reflection
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Atmospheric Refraction
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Atmospheric Refraction
Just like sound, light travels faster through hot air than cool air. The speeding up of the part of the wave nearest the ground produces a gradual bending of light rays.
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Atmospheric Refraction
The Sunset
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Atmospheric Refraction
At sunset, you can still see the sun after it is really below the horizon. The Earth’s atmosphere refracts (bends) the light. Every day, we get about 5 minutes of daylight more than we should.
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Dispersion in a Prism In a prism, different frequencies of light travel at different speeds. Red travels faster than blue light. So different frequencies (colors) refract differently and bend at different angles.
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Dispersion in a Prism Dispersion: The separation of light into colors arranged according to their frequency.
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The Rainbow Caused by dispersion of light by raindrops.
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The Rainbow When you move, your rainbow moves with you. Only you can see your rainbow.
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Total Internal Reflection
Total Internal Reflection: the reflection of all the light that strikes the boundary between two media. This will happen at the “Critical Angle.”
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Total Internal Reflection
Critical Angle: the angle in which a beam of light will reflect off of a boundary instead of transmit. Water has a critical angle of 48o. So if light within the water is more than 48o from the normal, the light will be totally internally reflected.
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Total Internal Reflection
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Total Internal Reflection
Optical Fibers (light pipes) Use total internal reflection to “pipe” light from one place to another.
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Lenses Converging and Diverging Lenses Image Formation by a Lens
Constructing Images Through Ray Diagrams Image Formation Summarized
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Lens A piece of glass that bends parallel rays of light so they cross and form an image. Principal Axis: the line joining the centers of curvature of its surfaces. Focal Length: the distance between the center of a lens and either focal point.
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Converging (Convex) Lens
A lens that bends incoming parallel rays so they converge to a single point. They are thicker in the middle than on the edges. Converging Focal Point: the point at which a beam of parallel light converges. Converging Focal Plane: the plane that passes through the focal point (perpendicular to the principal axis) where light can converge.
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Diverging (Concave) Lens
A lens that bends incoming parallel rays so they diverge from a single point. They are thinner in the middle than on the edges. Diverging Focal Point: the point from which the beam of light seems to come. Diverging Focal Plane: a beam appears to come from a point on a focal plane.
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Image Formation by a Lens
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