waves

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waves
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waves

• disturbance that transfers energy from place to
  place transmits energy through matter or space
• the matter through which a wave travels is a
  medium
• the medium through which the wave travels may
  experience some local oscillations as the wave
  passes, but the particles in the medium do not
  travel with the wave

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waves

• Transverse Waves
• the particle displacement is perpendicular to the
  direction of wave propagation

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waves

• Transverse Wave

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waves

• Longitudinal Waves
• the particle displacement is parallel to the
  direction of wave propagation

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waves

• Longitudinal Wave
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waves

• wave properties
• points A and F on the diagram represent the
  crests of this wave. The crest of a wave is the
  point on the medium which exhibits the maximum
  amount of positive or upwards displacement from
  the rest positon

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waves

• points D and I on the diagram represent the
  troughs of this wave. The trough of a wave is the
  point on the medium which exhibits the maximum
  amount of negative or downwards displacement from
  the rest positon

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waves

• the amplitude of a wave refers to the maximum
  amount of displacement of a a particle on the
  medium from its rest position
• the amplitude is the distance from rest to crest.
  Similarly, the amplitude can be measured from the
  rest position to the trough position.

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waves

• the wavelength of a wave is simply the length of
  one complete wave cycle
• represented by Greek letter lambda ?
• measured as the distance from crest to crest or
  from trough to trough

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waves

• a compression is a point on a medium through
  which a longitudinal wave is traveling which has
  the maximum density

                                                
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waves

• a region where the coils are spread apart, thus
  maximizing the distance between coils, is known
  as a rarefaction

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waves

• for longitudinal waves, wavelength can always be
  determined by measuring the distance between any
  two corresponding points on adjacent waves

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waves

• a wavelength measurement is made by measuring the
  distance from a compression to the next
  compression or from a rarefaction to the next
  rarefaction

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waves

• frequency of a wave refers to how often the
  particles of the medium vibrate when a wave
  passes through the medium
• represented by symbol f
• in mathematical terms, the frequency is the
  number of complete vibrational cycles of a medium
  per a given amount of time
• i.e. frequency means how many waves per second

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waves

• unit for frequency is the Hertz
• (abbreviated Hz)
• Hz is equivalent to 1 cycle/second
• 1 kilohertz 1 kHz 1,000 Hz 1 megahertz 1
  MHz 1,000,000 Hz 1 gigahertz 1 GHz
  1,000,000,000 Hz
• hertz is named after the German physicist,
  Heinrich Hertz (d. 1967)

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waves

• If a coil of slinky makes 2 vibrational cycles in
  one second, then the frequency is 2 Hz. If a coil
  of slinky makes 3 vibrational cycles in one
  second, then the frequency is 3 Hz. And if a coil
  makes 8 vibrational cycles in 4 seconds, then the
  frequency is 2 Hz
• (8 cycles/4 s 2 cycles/s)

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waves

• period of a wave is the time for a particle on a
  medium to make one complete vibrational cycle
• represented by symbol T
• period is the reciprocal of the frequency

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waves

• frequency 1 / period
• f 1 / T

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waves

• speed is the distance traveled by a given point
  on the wave (such as a crest) in a given interval
  of time
• wave frequency refers to the number of cycles
  occurring per second, wave speed refers to the
  meters traveled per second

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waves

• speed wavelength / period
• v ? / T
• if the crest of an ocean wave moves a distance of
  20 meters in 5 seconds, then the speed of the
  ocean wave is 4 m/s

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waves

• since the period is the reciprocal of the
  frequency,
• Speed Wavelength x Frequency
• v ? x f

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waves

• 1. Bill counts 5 waves on a pond in 10 s. The
  distance between them is 80 cm. What is their
  speed?
• 2. Lizi reads the back label of her microwave
  oven. It says frequency 2,450 MHz. The speed of
  microwaves is 3.00108 m/s. What wavelength are
  they?
• 3. Paul plays a note of wavelength 25 cm on his
  synthesizer. He knows the speed of sound is
  340 m/s in air. What is its frequency?

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waves

• 1. 5 waves in 10 s. Distance between is 80 cm.
  Speed? frequency 5/10 05 Hz. speed
  frequency wavelength
• 05 80 40 cm/s

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waves

• 2. frequency 2,450 MHz. speed 3.00108 m/s.
  speed frequency wavelength 3.00108
  2,450106 wavelength wavelength 3.00108
  2,450106 0122 m 122 cm

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waves

• 3. wavelength 25 cm 025 m. Speed 340 m/s
  speed frequency wavelength 340 frequency
  025 frequency 340 025 1,360 Hz

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waves summary

• Waves all transfer energy from one place to
  another. They do this by vibrating something
• There are two types of waves longitudinal and
  transverse. Most waves are transverse.
• Longitudinal waves have vibrations in the same
  direction as the wave motion.

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waves summary

• Transverse wave vibrations are at 90 to the
  direction of the wave.
• Wavelength is the distance from one part of a
  wave and the same point on the next wave along.
  e.g. peak to peak.
• Amplitude is the maximum movement from the
  original position. For transverse waves this is
  the height of the wave from the middle.

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waves summary

• Frequency is the number of waves per second and
  it is measured in hertz (Hz).
• The speed of a wave can be found by using this
  formula v ? x f