Behavior of Light Waves

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Behavior of Light Waves
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S8P4.b

• Describe how the behavior of light waves is
  manipulated causing reflection, refraction,
  diffraction, and absorption
• Manipulate to affect or control

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Whats It Mean?

• Light waves change when they hit materials.
• The way light waves change depends on the
  material the waves hit.
• Describe how changes in light waves cause
  reflection, refraction, diffraction, and
  absorption.

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Getting the Idea

• Waves do not always travel in one direction they
  often bounce off one surface and then travel in
  another direction.
• Waves can continue to change direction long after
  the original source of the energy has stopped.

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• When sound waves demonstrate this property, you
  hear echoes.
• Light waves can also bounce off surfaces and
  change the direction in which they travel.
• When any type of wave hits and obstacle or passes
  from one medium to another, it is possible that
  the wave will change in speed, direction, or
  shape.

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Reflection

• Occurs when a wave bounces back after striking a
  barrier.
• Examples of barriers include mirrors and shiny
  pieces of metal.
• Water waves, light waves, sound waves, and heat
  all can be reflected.
• An echo is a reflected sound wave.
• Reflection is the property of light that allows
  you to see yourself in a mirror.

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Law of Reflection

• States that the angle of incidence is equal to
  the angle of reflection.

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Absorption of Light

• A beam of light becomes dimmer partially because
  of absorption and scattering.

• Absorption is the transfer of energy to particles
  of matter.

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• When you shine a flashlight in the air, the air
  particles absorb some of the energy form the
  light. This causes the light to become dim.

• The farther the light travels from the
  flashlight, the more it is absorbed by air
  particles.

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Scattering of Light

• The releases of light energy by particles of
  matter that have absorbed energy.
• When the light is released, it scatters in all
  directions.
• Light from a flashlight is scattered out by air
  particles. The scattered light allows you to see
  objects outside the beam. However, because light
  is scattered out from the beam, the beam becomes
  dimmer.

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Why is our sky blue?

• The gases and other particles that make up our
  atmosphere scatter the color blue more than the
  other six colors.

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Refraction

• The bending of a wave as it passes at an angle
  from one medium to another.

A hands lens makes objects appear larger because
of refraction.
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Refraction

• The bending of a wave as it passes at an angle
  from one medium to another.
• Refraction of light takes place when light passes
  from one medium having one density to a medium
  with a different density.
• The refraction of light occurs because the speed
  of light varies depending on the material that it
  passes.

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Light travels more slowly through the glass and
water than it does air. Therefore, it refracts
as it passes at an angle from air to glass, to
water or from water, to glass, to air.
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Optical Illusions

• Stare at the four dots in the center of this page
  for about 30 seconds.  Try not to blink.  Then
  lean back, look at the ceiling and blink your
  eyes a few times.  Did you see Jesus?
•  

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Refraction and Color Separation
White light can be separated into different
colors (Roy G. Biv) by refraction.

• When white light is refracted, it separates into
  different colors.
• Color separation during refraction is responsible
  for the formation of rainbows.

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What causes a rainbow?

• Rainbows are created when sunlight is refracted
  by water droplets in the atmosphere.

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Diffraction

• refers to the bending, spreading, and
  interferences of waves when they go through a
  narrow opening.
• Occurs with any type of wave.
• A wave is diffracted more when its wavelength is
  similar in size to the barrier or opening.

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Transmission

• The passing of waves through a medium.
• Example A radio wave (electromagnetic wave) is
  produced at the radio station. The wave travels
  from the radio stations transmitter out in all
  directions at the speed of light. Your radio
  detects the EM