Welcome to 306!

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Welcome to 306!

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  Integrated Science for the second marking period.

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Types of Waves

• Section 11.1

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Waves

• A disturbance that transmits energy through
  matter or space

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Waves

• Most waves move through matter called a medium.
• Ex. Waves traveling through water.

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Types of Waves

• 1. Mechanical Waves
• a wave that requires a medium through which to
  travel
• Most type of waves
• Ex. Sound, seismic

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Types of Waves

• 2. Electromagnetic Waves
• waves caused by the disturbance in electric and
  magnetic fields and that does not require a
  medium.
• (light radiation waves)

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What do Waves Do?

• When waves travel through media they are doing
  work (energy transferred).
• Ex. Sound traveling in your ear causes vibrates
  throughout your ear

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What do Waves Do?

• Ex. Shock waves move the earth during an
  earthquake.
• Ex. Tsunami waves move anything in their path

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Shock wave from breaking the sound barrior.
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How a Wave Travels

• As wave travels in air, the waves spread out in
  spheres
• the sphere will get bigger and bigger as they
  move farther away

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How a Wave Travels

• Why is it more damaging to your ears if you are
  standing next to a speaker rather than a 100
  meters away?

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How a Wave Travels

• Each sphere carries the same amount of energy
• But the energy is more spread out of a greater
  distance.

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Speaker
Sound waves
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Vibrations and Waves

• Most waves are caused by a vibrating object,
  which will then cause other objects to vibrate
• Vibrations will transfer energy from PE to KE.

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Vibrations and Waves

• simple harmonic motion--vibration would continue
  forever
• Damped harmonic motion transfers the energy and
  the vibration will fade out.
• Ex. Shock absorbers on cars and bikes.

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Wave Vibration Types

• 1. Transverse Waves
• -a wave that causes the particles of the medium
  to vibrate perpendicular to the direction of the
  wave.
• The Wave at a stadium is a good illustration.
• Ex. Light waves

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Wave Vibration Types

• 2. Longitudinal Waves
• -a wave that causes the particles of the medium
  to vibrate parallel to the direction of the wave.
• they expand and compress.
• Ex. Sound waves

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Wave Vibration Types

• 3. Surface Waves
• -waves that are both transverse or longitudinal.
• -Circular motion
• -ex. Ocean waves

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Wave Types

• Mechanical waves
• -can be transverse, longitudinal , or surface
  waves
• Electromagnetic (light)
• -waves will only be transverse.

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Characteristics of Waves

• 11.2

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Wave Properties

• all transverse waves have similar shapes, no
  matter the size of the wave.
• The shape is called a sine curve or sine
  wave.

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Sine Wave
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Wave Parts

• Crest
• Highest point of a transverse wave
• Trough
• lowest point of a transverse wave

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Wave Parts

• Amplitude
• -The vertical distance that particles vibrate
  from their normal position when a wave passes
• measures the intensity of wave.
• -ex. Loudness, brightness

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Wave Parts

• Wavelength
• -The distance between any two successive
  identical parts of a wave
• Represented by the symbol lambda (?)
• Measured in a degree of meters

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Wave Diagram
Wavelength
Amplitude
Crest
trough
Wavelength
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Wave Properties

• 1. Wavelength
• -measures the size of the wave

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Wave Properties

• 2. Amplitude
• -measures the intensity (strength) of the wave

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Wave Properties

• 3. Frequency
• -the number of full wavelengths that pass a point
  in a particular period of time (rate)
• -Represented by the symbol (ƒ)
• -Measured in hertz (Hz) beat/sec
• -Your radio dials are in megahertz

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Wave Properties

• 4. Period (time)
• -The time required for one full wavelength to
  pass a certain point
• -Represented by the symbol (T)
• -Measured in seconds

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Low
Low
Wavelength
High
High
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Frequency, wavelength, and Period

• Wavelength and period will increase when
  frequency decreases.
• ? ?, T, ?, then f ?

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Frequency and Period

• You can calculate frequency and period from each
  other
• T1/f or f1/T

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Frequency and Sound

• We hear sounds from the range 20 Hz to 20,000 Hz
• determines the pitch

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Pitch and Loudness
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Frequency and Light

• We see light from the range 4x1014 Hz red to
  8x1014 Hz violet
• Frequency determines the energy and color
• Red is the easiest to see, violet is the hottest
  (most energetic)

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Wave Properties

• 5. Wave Speed
• -the speed at which a wave passes through a
  medium.
• -Waves travel at different speeds in different
  media phases (s, l, g).

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Mechanical Wave Speed

• These waves travel fastest in solids and the
  slowest in gases
• Why? (essay question)

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sonic boom
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Light Wave Speed

• all electromagnetic waves travel at the same
  speed in empty space. (3 x 108 m/s)
• Light waves slow down as they pass through media.

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Wave Speed Equations

• Speedwavelength/period
• v?/T
• Can also use
• Speedfrequency x wavelength
• v f x ?

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Examples

• A piano string vibrates with a frequency of 264
  Hz. If the waves have a wavelength of 1.3 m,
  what is the speed of sound in air?

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Examples

• v ? f
• speed (1.30 m) (264 Hz)
• speed 343 m/s

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Examples

• A string with a
• wavelength of 1.30 m and
• a period of 0.00379 s is
• played. What is the
• speed of the wave?

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Examples

• V ?/T
• speed1.30 m/0.00379 s
• speed 343 m/s

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Doppler Effect

• an observed change in the frequency of a wave
  when the source or observer is moving
• Object approaches with high frequency but low
  wavelength, but as it passes the frequency lowers
  as the wavelength increases

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Doppler effect
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Standing Waves

• wave that appears not to move along the medium.
• two regions

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Standing Waves

• Regions of no vibrations (nodes)
• Regions of maximum vibration (antinodes)

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Wave Interactions

• 11.3

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1. Reflection

• The bouncing back of a wave as it meets a surface
  or boundary

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2. Diffraction

• When waves pass through an opening or by an edge
  the bend around the edge or expand as they pass
  through the opening.

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3. Refraction

• The bending of waves as they pass from one medium
  to another

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Refraction

• Air to water is an example
• Ex. Spoon seeming to bend when placed in water

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4. Interference

• The combination of two or more waves that exist
  in the same place at the same time.
• Once waves pass, they return to original shape

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Interference

• Two types
• Constructive
• destructive

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Constructive Interference

• The crests of wave line up to combine their
  amplitudes making the wave larger.
• Wave becomes bigger

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Constructive Interference

• The new wave is bigger than the original when
  waves combine

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Destructive Interference

• When crest of one wave meets the trough of
  another wave
• Forms a smaller wave than the original

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Interference of Light Waves

• When light waves interfere with each other,
  colorful displays are produced.
• Soap bubbles

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Interference of Sound Waves

• When two waves with different frequencies
  interfere with each other, beats are produced

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