Wave Interference

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Wave Interference
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Wave Interference

• align waves in time and add the amplitudes
• known as the principle of superposition
• amplitudes can be either ve or -ve
• if the amplitudes are of the same sign, the wave
  is reinforced and grows bigger
• if the amplitudes are of opposite sign, the wave
  is diminished and grows smaller

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Wave Interference

• works for both longitudinal waves and for
  transverse waves

constructive interference
destructive interference
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Wave Interference
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• so far, we have only looked at waves that have
  the same wavelength or frequency
• what if amplitudes or frequencies are different?
• again, we simply add the two waves together to
  see what results
• interfering pulses
• more interfering pulses
• interfering waves

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Wave Interference

• produces beats
• this is how musicians tune their instruments to
  match in the orchestra

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A few things we need to know

• understand what we mean by pulse, boundary,
  transmission, reflection
• know that when a pulse meets a boundary some of
  the wave continues through (transmission) and
  some bounces back (reflection)
• know that the reflected portion is sometimes on
  same side as original pulse and sometimes on
  other side
• boundary simulation

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Standing Waves
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Standing Waves
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Guitar Strings
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Music

• what makes instruments unique is the combination
  of harmonics produced by the different
  instruments.
• flutes produce primarily the 1st harmonic
• they have a very pure tone
• oboes produce a broad range of harmonics and
  sound very different

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Combining Waves
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Combining More Waves