Chapter 1 Characteristics of Waves

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Chapter 1 Characteristics of Waves

• Section 3
• Interactions of Waves

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Reflection

• Reflection

When a wave hits a surface it cannot pass
through, it bounces back
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Reflection Continued

• Ex ball bouncing against wall, mirrors, and
  echoes.

Law of Reflection The angle of incidence equals
the angle of reflection.
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Refraction

• Refraction

When a wave enters a new medium at an angle, one
side of the wave changes speed before the other.
This causes the wave to bend.
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Refraction Continued

• Note Bending only occurs when the wave hits the
  new medium at an angle because the two sides of
  the wave are traveling at different speeds. If
  the wave enters at 90 degrees, no bending occurs.

Ex rainbows, looking at an object underwater,
and rolling a pencil.
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Reflection and Refraction
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Diffraction

• Diffraction When a wave moves around a barrier
  or through an opening in a barrier, it bends and
  spreads out.

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Diffraction Continued

• Ex Waves in a harbor and sound through a doorway.

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Interference

• Interference The interaction between waves when
  they meet.

Two Types Constructive Interference
and Destructive Interference
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Interference ContinuedConstructive Interference

• Constructive Interference When waves combine to
  form a wave with a larger amplitude. Waves
  continue as if they had not met.

Note Construction Build
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Interference ContinuedConstructive Interference

• Notice, when crests overlap, the crest becomes
  higher. When troughs overlap, they trough
  becomes deeper.

The amplitude increases.
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Interference ContinuedDestructive Interference

• Destructive Interference When two waves combine
  to form a wave with a smaller amplitude. Waves
  continue as if they had not met.

Note Destructive Destroy
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Interference ContinuedDestructive Interference

• Notice when a crest and a trough overlap, they
  subtract.
• For example, if a larger crest meets a smaller
  trough, the resulting crest is smaller than the
  original.

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Standing Waves

• Standing Waves If the incoming wave and the
  reflected wave have the right frequency they
  produce a combined wave that appears to be
  standing still.
• Ex guitar string.

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Standing Waves Continued

• Nodes On a standing wave, where amplitude is
  zero. Or, where the lines cross

Antinodes On a standing wave, where amplitude
is at its maximum. Or, the top of crests and
bottom of troughs
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Standing Waves ContinuedResonance

• Resonance When external vibrations match an
  objects natural frequency.

Ex musical instruments.
Most objects have at least one natural frequency.
This includes wine glasses.