Properties of

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Properties of
MT 5 LT 2
Waves
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Review
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Basic Properties of Transverse Waves

• Amplitude
• Wavelength
• Frequency
• Speed

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Amplitude

• Amplitude is the distance from the rest to crest
  or rest to trough.
• Farther medium moves as it vibrates, larger the
  amplitude.
• Greater the amplitude, greater the amount of
  energy

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Wavelength

• Wave travels certain distance before it starts to
  repeat.
• Distance between 2 corresponding parts of a wave
  .
• Transverse
• measure from crest to crest or trough to trough.

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Wave Height

• The distance from one crest to one trough (trough
  to crest too)

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Properties of Longitudinal/Compressional Waves
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Longitudinal Wave

• The motion of the medium vibrates in the same
  direction (parallel) as the wave travels.
• Example Slinky

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Longitudinal Wave

• Compressions
• The parts where the coils are close together
• Rarefactions
• the parts where the coils are spread out

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Amplitude of a longitudinal wave.

• The amplitude of a longitudinal wave is a measure
  of how compressed or rarefied the medium becomes.

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Wavelength

• Distance between 2 corresponding parts of a wave.
• Longitudinal measure from one compression to the
  next.

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How do waves interact?

• Wave Behaviors

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What happens when

• Wave Behaviors

• A wave meets a hard surface like a wall?
• A wave enters a new medium?
• A wave moves around an obstacle?
• A wave meets another wave?

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Ways Waves Interact

• Refraction
• Diffraction
• Interference
• Constructive
• Destructive
• Reflection
• Doppler Effect
• Polarization

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Refraction

• What is it?
• The bending of wave as it enters a new medium.
• Why does it doe this?
• All waves change speed when they enter a new
  medium.
• Greater change in speed, more bending of wave!

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Refraction
Ex Pencil half in water, half in air and it
looks bent
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Reflection

• What happens when a wave hits a wall or some
  other fixed object?
• To find out, tie a rope to the back of a chair.
  Gently shake the rope up and down once to send a
  single pulse along the rope as shown. Observe
  what happens when the pulse hits the chair.

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Reflection

• Gently shake the rope up and down once to send a
  single pulse along the rope as shown. Observe
  what happens when the pulse hits the chair.

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Reflection

• 1. What happened to the direction of the pulse
  when it hit the chair?
• 2. How did the orientation of the reflected pulse
  compare to the original pulse?

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Reflection

• What is it?
• When a wave hits a surface through which it
  cannot pass, it bounces back
• All types of waves can be reflected
• If reflection occurs at a fixed boundary, the
  reflected wave will be upside down compared to
  the original wave.

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Diffraction

• What is it?
• The bending of wave as it moves around a barrier
  or passes through a hole in a barrier.
• The larger the wavelength, the more it diffracts
• The wave will try to curve around the boundary or
  outward through the opening

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Interference

• What is it?
• When two or more waves are moving through a
  medium at the same time, they may overlap or
  combine together.
• There are two types
• Constructive interference
• Destructive interference

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Constructive Interference

• Constructive interference occurs whenever two
  waves combine to make a wave with a larger
  amplitude.

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Constructive Interference

• Example You and another person each send a wave
  of equal frequencies from each end of a jump rope

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Destructive Interference

• Destructive interference when the amplitudes of
  two waves combine producing a smaller amplitude.

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Destructive Interference

• Example A muffler on a car

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Standing waves

• If the incoming wave and the reflected wave
  combine at the right places the combined wave
  appears to be standing still.
• It appears to be standing in one place, even
  though it is two waves interfering as they pass
  through each other.

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Take a few minutes and fill this out..
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You should have.

• a. If reflection occurs at a fixed boundary, the
  reflected wave will be upside down compared to
  the original wave because
• b. Refraction occurs when a wave enters a new
  medium at an angle because one side of a wave
  front moves more slowly than the other side.
• c. The larger the wavelength is compared to the
  size of an opening or obstacle, the more a wave
  diffracts.
• d. The types of interference are constructive and
  destructive interference.
• Constructive is when two waves combine and the
  amplitude increases Destructive is when two waves
  combine and the the amplitude decreases
• e. A standing wave forms only if a multiple of
  one half wavelength fits exactly into the length
  of the vibrating object.

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Nodes and Antinodes

• Nodes at certain points, destructive
  interference causes the two waves to combine and
  produce an amplitude of zero.

• Antinodes are the points of maximum energy. The
  crests and troughs of a standing wave.

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Resonance

• Most objects have a natural frequency of
  vibration. Resonance occurs when vibrations
  traveling through an object match the objects
  natural frequency.
• An object that is vibrating at its natural
  frequency absorbs energy from the objects that
  vibrate at the same frequency. Occurs in music.

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Doppler Effect

• Change in pitch of a sound source due to the
  relative motion of the source and the observer.
• Observed when a police car, w/sirens blaring,
  passes you traveling in the opposite direction at
  a high speed.
• Pitch of sirens is high when approaches you
  wavelengths are shorter, and frequency is higher
• Pitch of sirens drops to lower pitch as it passes
  you wavelengths are longer, and frequency is
  lower

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Doppler Effect
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Polarization

• ONLY with Transverse waves.
• If a transverse wave is linearly polarized, then
  the transverse vibrations in the wave are all in
  the same direction. Light is frequently used as
  an example of polarization.