Wave Interactions

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Wave Interactions
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Can you see me now?

• Transparent materials allow waves to pass through
  them with little or no distortion
• Translucent materials allow waves to pass through
  them with varying degrees of distortion
• Opaque materials do not allow waves to pass
  through them
• Waves must be reflected or absorbed

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Categories

• Reflection
• Refraction
• Diffraction
• Absorption
• Interference
• Constructive Interference
• Destructive Interference

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Reflection

• Reflection is when a wave bounces off of a
  surface
• Some of the energy may be absorbed, but most is
  reflected
• LAW OF REFLECTION
• The angle of incidence MUST EQUAL the angle of
  reflection

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Mirror, mirror

• Explains why a mirror must be smooth
• So that all the angles line up to make a clear
  picture in the reflection
• Water surfaces may not be smooth, produce a
  distorted reflection

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Mirror, etc.
Chalkboard, etc.
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Shaped Mirrors

• Concave
• caved in
• Light rays, etc., converge in the center
• Make the image larger or focus energy
• Parabolic dishes
• Satellite dishes
• Lighting the Olympic Torch

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Shaped Mirrors

• Convex
• curved out
• Light rays, etc., spread out from the center
• Images look smaller, but cover more area

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Refraction

• Refraction is when a wave bends as it moves from
  one medium to another
• Edges of the wave slow down in a more dense
  medium and speed up in a less dense medium
• The wave front bends towards the normal in a more
  dense medium, and
• away from the normal in a less dense medium

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Refraction can depend on the angle the wave hits
the medium
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Oil-slick Rainbows

• Because of the different densities of oil,
  gasoline, water, and air, a rainbow-like
  refraction can form in puddles near well-traveled
  parking lots

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Lenses

• Controlling the bend of the light allows us to
  make lenses

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Diffraction

• Bending of waves around a barrier

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With two barriers, BOTH edges bend the waves
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Jetties are false walls to bend the ocean waves
towards the shore
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Interference

• Whenever two waves of the same kind pass through
  each other, they interfere
• Constructive Interference
• If their crests and troughs line up, they are
  said to be in phase
• Destructive Interference
• If these points dont, they are out of phase
• Should they be exactly out of phase, the waves
  will cancel each other out

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