Waves Chapter 14

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WavesChapter 14

• Two methods of energy transfer
• Transfer of matter
• Wave motion

Wave A rhythmic disturbance that carries
energy through matter and space.
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WavesChapter 14

• Two types of waves
• Mechanical-Need a medium to which they transfer
  energy
• Electromagnetic-Do not need a medium to which
  they transfer energy

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WavesChapter 14

• Waves are also classified on how they transfer
  matter
• Transverse Waves-Causes the particles to vibrate
  perpendicular to the direction of motion.
• Longitudinal (Compressional) -Causes the
  particles to vibrate parallel to the direction of
  motion.

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Wave Motion
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WavesChapter 14

• Characteristics of Waves
• Wavelength (?) The linear distance between
  corresponding points on corresponding waves.
• Frequency (f) The number of wavelengths that pass
  a given point per unit time.
• Period (T) The time it takes for one pulse to
  pass a given point. (T1/f)

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WavesChapter 14

• Characteristics of Waves (continued)
• 4. Pulse - A single disturbance in a
  medium.
• 5. Amplitude - The point of maximum
• displacement from the rest position.

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Transverse Wave
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Waves Chapter 14
Longitudinal Wave
Compression The compressed portion of
longitudinal wave
Rarefaction The elongated portion of
longitudinal wave
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Animation
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Chapter 14Waves

v velocity f frequency ? wavelength
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Chapter 14Waves

An observer determined that 2.5 meters separate a
trough and an adjacent crest of a surface wave
from a boat. 33 crests passed a point in 30
seconds. What is the speed of the wave?
v f 33/30 1.1 hz ? (2.5 m 2) 5 m
v f?
v (1.1 hz)(5 m) 5.5 m/s
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Chapter 14 Waves
The period of the wave is 3 seconds. Find the
velocity of the wave.
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Chapter 14Waves

• The speed of a wave depends on the medium
• Electromagnetic Waves 3 x 108m/s
• Sound Waves in Air 330 m/s
• Sound Waves in Water 1498 m/s
• Sound Waves in Glass 4540 m/s
• Sound Waves in Steel 5200 m/s

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Chapter 14Waves
Interference - The combining of two or more
waves arriving at the same point at the same time.
Node - A point in the medium which remains
undisturbed when acted upon one or more
disturbances simultaneously
Antinode - A point of maximum displacement in
the medium when acted upon one or more
disturbances simultaneously
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Chapter 14Waves
A pulse passing from a less rigid medium to a
more rigid medium produces a reflected pulse
that is inverted (180º out of phase).
A pulse passing from a more rigid medium to a
less rigid medium produces a reflected pulse
that is erect.
demonstration
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Constructive Interference
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Destructive Interference
Interference
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Chapter 14Waves
Standing Waves - A wave whose nodes are
stationary.
Standing Wave
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Chapter 14 Waves
Superposition Principle The displacement of a
wave caused by two or more waves is the
algebraic sum of the individual waves.
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Chapter 14Waves

• Reflection-The return of a wave as it comes back
  from a medium.
• Refraction-Change in direction of a wave as it
  passes from one medium to another.
• Diffraction-Bending of waves around an object.

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Interference
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