Waves

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Waves

• 23.3 Wave Motion
• pp. 567- 571

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23.3 Wave Motion

• A wave front is the leading edge of a moving wave
  which is considered to be the crest for purposes
  of modeling.
• The crests of a plane wave look like parallel
  lines.
• The crests of a circular wave are circles.

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23.3 Four wave interactions

• When a wave encounters a surface, four
  interactions can occur
• reflection,
• refraction,
• diffraction, or
• absorption.

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23.3 Wave interactions

• A boundary is an edge or surface where things
  change.
• Reflection, refraction, and diffraction usually
  occur at boundaries.

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REFRACTION

• The bending of a wave as it passes at an angle
  from one medium to another is called refraction.
• The speed of a wave changes depending on the
  medium in which it is traveling

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23.3 Wave interactions

• Diffraction usually changes the direction and
  shape of the wave.
• When a plane wave passes through a small hole
  diffraction turns it into a circular wave.

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23.3 Wave interactions

• Absorption is what happens when the amplitude of
  a wave gets smaller and smaller as it passes
  through a material.
• The wave energy is transferred to the absorbing
  material.
• Curtains in theaters absorb backstage sounds so
  the audience doesnt hear them.

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23.3 Transverse waves

• The oscillations of a transverse wave are not in
  the direction the wave moves. They are
  perpendicular to the direction of the wave
  movement.

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23.3 Longitudinal waves

• The oscillations of a longitudinal wave are in
  the same direction that the wave moves.

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23.3 Constructive interference

• Constructive interference happens when waves add
  up to make a larger amplitude.
• Suppose you make two wave pulses on a stretched
  string.
• One comes from the left and the other comes from
  the right.
• When the waves meet, they combine to make a
  single large pulse.

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23.3 Destructive interference

• What happens when one pulse is on top of the
  string and the other is on the bottom?
• When the pulses meet in the middle, they cancel
  each other out.
• During destructive interference, waves add up to
  make a wave with smaller or zero amplitude.

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