What is refraction?

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What is refraction?
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    Light Bends!
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Light Moves Slower
Light Moves Faster
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Refraction is the bending of light as it enters a
new medium.
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More About Light!
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WHY DOES LIGHT SLOW DOWN????

• Each time the photons bump into a particle of the
  medium, the light gets absorbed which causes the
  particle to vibrate a little and then the light
  gets re-emitted.
• This process causes a time delay in the light's
  movement so the more particles there are (the
  more dense the medium), then the more the light
  will be slowed down.

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Light Waves are Transverse Waves
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How is Light Different Than Sound

• Light waves do NOT require a medium to travel
  though.
• In fact, light travels the quickest through a
  vacuum, where no matter exists!
• Light rays from the sun take about 8 minutes to
  reach Earth. (Thats 150 million kilometers in 8
  minutes!)
• The speed of light is about 1 million times
  faster than the speed of sound. 300,000 km/s to
  be exact.

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Its Storming!

• You see the light almost instantly, but you dont
  hear the thunder until seconds later.

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Reflection

• Light shines on objects and reflects off of them.
  
• When waves reflect, they can scatter. Think of
  an echo-the reflected sound is distorted.
• Waves travel in all directions. When they reflect
  off of a surface that isnt smooth, the sound
  reflects in many directions and doesnt all reach
  your ear at the same time.

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What causes a distorted (strange) image or sound
from reflected light or sound waves?
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Diffraction

• Waves change direction when they pass through an
  opening or around something in their path.
• You cannot block out sound from your ears with
  your hands, but you can block light from your
  eyes with your hands!

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ELECTROMAGNETIC RADIATION
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ELECTROMAGNETIC RADIATION
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Wave-Particle Duality

• Sometimes its easier to think of electromagnetic
  radiation as waves.
• Other times its easier to think of
  electromagnetic radiation as particles called
  photons.

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HOW DO WE KNOW???

• Today scientists define light as a collection of
  one or more photons moving through space as
  electromagnetic waves.
• Light travels away from a source
• as an electromagnetic wave.
• When it encounters the slits,
• it diffracts and divides into two wave fronts.
• These wave fronts overlap and approach the
  screen. At the moment of impact, however, the
  entire wave field disappears and a photon
  appears.

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