An Introduction to Waves

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An Introduction to Waves

• 3U Physics

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What is a wave?

• A wave is a disturbance which carries energy from
  one location to another.

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What is a wave?

• A wave is a disturbance which carries energy from
  one location to another.
• The material the disturbance travels through is
  the ?
• The movement of the disturbance is referred to as
  ?

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What is a wave?

• A wave is a disturbance which carries energy from
  one location to another.
• The material the disturbance travels through is
  the medium.
• The movement of the disturbance is referred to as
  ?

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What is a wave?

• A wave is a disturbance which carries energy from
  one location to another.
• The material the disturbance travels through is
  the medium.
• The movement of the disturbance is referred to as
  propagation.

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2 Types of Waves

• A longitudinal wave is a wave in which the
  particles of the medium move in a direction
  parallel to the direction of propagation.

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2 Types of Waves

• A longitudinal wave is a wave in which the
  particles of the medium move in a direction
  parallel to the direction of propagation.

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2 Types of Waves

• A longitudinal wave is also called a pressure
  wave or a sound wave.

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2 Types of Waves

• A longitudinal wave is also called a pressure
  wave or a sound wave.
• The regions of increased pressure/density are
  called ?.
• The regions of decreased pressure/density are
  called ?.

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2 Types of Waves

• A longitudinal wave is also called a pressure
  wave or a sound wave.
• The regions of increased pressure/density are
  called compressions.
• The regions of decreased pressure/density are
  called ?.

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2 Types of Waves

• A longitudinal wave is also called a pressure
  wave or a sound wave.
• The regions of increased pressure/density are
  called compressions.
• The regions of decreased pressure/density are
  called rarefactions.

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2 Types of Waves

• A transverse wave is a wave in which the
  particles of the medium move in a direction
  perpendicular to the direction of propagation.
• Although sound waves are not transverse waves, we
  often represent them as transverse waves because
  transverse waves are easier to draw.

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2 Types of Waves

• The vertical axis represents not displacement but
  pressure.

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Snapshot of a Transverse Wave

• The dashed line represents the equilibrium
  position of the particles.

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Snapshot of a Transverse Wave

• The positions of maximum displacement are
  referred to as crests (positive displacement) and
  troughs (negative).
• The maximum displacement is the amplitude.

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Snapshot of a Transverse Wave

• The positions of maximum displacement are
  referred to as crests (positive displacement) and
  troughs (negative).
• The maximum displacement is the amplitude.
• Amplitude Energy

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Snapshot of a Transverse Wave

• The distance between one crest and the next crest
  (or one trough and the next trough) is the

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Snapshot of a Transverse Wave

• The distance between one crest and the next crest
  (or one trough and the next trough) is the
  wavelength, represented by

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Snapshot of a Transverse Wave

• The distance between one crest and the next crest
  (or one trough and the next trough) is the
  wavelength, represented by l.

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Snapshot of a Transverse Wave

• The time it takes one complete wavelength to pass
  a single point is the

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Snapshot of a Transverse Wave

• The time it takes one complete wavelength to pass
  a single point is the period, represented by

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Snapshot of a Transverse Wave

• The time it takes one complete wavelength to pass
  a single point is the period, represented by T.

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Snapshot of a Transverse Wave

• The time it takes one complete wavelength to pass
  a single point is the period, represented by T.

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Snapshot of a Transverse Wave

• The number of complete wavelengths that pass a
  single point in one second is the frequency,
  represented by f.

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Frequency

• Frequency is measured in units of 1/s or s-1
• or Hertz (Hz).

I do not think that the wireless waves I have
discovered will have any practical application.
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Wave Speed

• The speed of a wave is therefore

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Wave Speed

• The speed of a wave is therefore

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Wave Speed

• The speed of a wave is therefore

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Wave Speed

• The speed of a wave is therefore
• The speed of a sound wave in air at room
  temperature (20oC) is 344 m/s.

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Sound Wave Example

• Calculate the wavelength of the sound wave
  produced by a 125 Hz tuning fork in air at 20oC.

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Sound Wave Example

• Calculate the wavelength of the sound wave
  produced by a 125 Hz tuning fork in air at 20oC.

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Sound Wave Example

• Calculate the wavelength of the sound wave
  produced by a 125 Hz tuning fork in air at 20oC.

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More Practice

• Inquiry Activity Slinky Waves
• Homework An Introduction to Waves