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WAVES

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WAVES Chapter 7 What is a wave A wave is A rhythmic disturbance Carries ENERGY but not MATTER How can a wave carry energy without carrying matter? – PowerPoint PPT presentation

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Title: WAVES


1
WAVES
  • Chapter 7

2
What is a wave
  • A wave is
  • A rhythmic disturbance
  • Carries ENERGY but not MATTER

3
How can a wave carry energy without carrying
matter?
  • Even though the ball is moving from one end of
    the line to the other, the people are not moving
    with it.

4
How do waves move
  • Mechanical Waves
  • Move through matter
  • Energy moves from
  • particle to particle
  • Examples
  • Water waves
  • Sound waves
  • Earthquake waves

5
How do waves move
  • Electromagnetic Waves
  • Move through empty space
  • Do not require matter or particles in order to
    move
  • Example
  • Light waves

6
Types Of Waves
  • Compressional (or Longitudinal) Waves
  • Transverse waves

7
Parts Of A Wave
CREST
high point of a transverse wave
AMPLITUDE
half the distance between the crest and trough
WAVELENGTH
TROUGH
distance from top of one crest to the top of the
next OR from one trough to the next
low point of a transverse wave
8
Properties of waves
  • Amplitude tells how much ENERGY the wave is
    carrying
  • Bright light has higher amplitude than dim
  • Loud sounds have higher amplitude than soft
  • Large water waves carry more energy than small
    ones

9
Properties of waves
  • Wavelength (?)
  • In visible light, ? determines color

?
?
Red has a longer
Violet has a shorter
?
Radio waves and microwaves have longer
?
X-rays and gamma ray have shorter
10
Properties of waves
  • Frequency the number of ? that pass a given
    point in one second, measured in ?/sec hertz
  • Higher frequency indicates faster vibration of
    whatever is generating the wave

11
Properties of waves
  • Frequency and wavelength are closely related
  • Short ? creates a higher frequency
  • In sound, this causes a higher pitch
  • In light, violet color has a higher frequency
    than red
  • Long ? creates a lower frequency
  • In sound, this causes a lower pitch
  • In light, red color has a lower frequency than
    violet

gt F lt ?
12
Properties of waves
WAVE SPEED
  • Mechanical Wave
  • Travels faster through solids because molecules
    are closer together and transmit the sound better
  • Electromagnetic Wave
  • Travels faster through empty space because there
    are no molecules in the way to slow it down

13
Wave Behavior
  • Reflection a wave strikes a surface and bounces
    off

HELLOOOO!!!
HELLOOOO!!!
Reflection are clear when they bounce off a
smooth, even surface. From a rough surface, light
scatters in all directions and the reflection is
distorted.
When sound waves reflect from a surface, it
produces an ECHO.
14
Wave Behavior
  • Refraction The bending of a wave as it moves
    from one medium into another because of a change
    in SPEED.

15
Wave Behavior
  • Diffraction The bending of waves around a
    barrier.

LIGHT WAVES Light waves do not diffract as much
as sound waves, so you cant see around corners.
This is because the ? of light is so much
smaller than the width of a door. Diffraction
occurs better when the barrier and ? are similar
in size.
SOUND WAVES You can hear sounds from a room even
when you are not in the room because the sound
waves bend as they pass through the open doorway
WATER WAVES When water waves strike obstacles
such as islands, they bend around the island and
keep moving. If the island was much bigger than
than the wavelength of the water wave, less
diffraction would occur
16
Wave Behavior
  • Interference The ability of two waves to combine
    and form a new wave when they overlap

17
INTERFERENCE
  • CONSTRUCTIVE Interference

18
INTERFERENCE
  • CONSTRUCTIVE Interference

19
INTERFERENCE
  • CONSTRUCTIVE Interference

20
INTERFERENCE
  • DESTRUCTIVE Interference

21
INTERFERENCE
  • DESTRUCTIVE Interference

22
INTERFERENCE
  • DESTRUCTIVE Interference

23
Constructive INTERFERENCE
  • The crests of two waves A B approach each
    other
  • The two waves form a wave with a greater
    amplitude while the crests of both waves overlap

24
Constructive INTERFERENCE
  • The original waves pass through each other and go
    on as they started.

25
Destructive INTERFERENCE
  • The crest of one wave (A) approaches the trough
    of another (B)
  • If the two waves have equal amplitude, they
    momentarily cancel when they meet

26
Destructive INTERFERENCE
  • The original waves pass through each other and go
    on as they started.

27
Parts Of A Wave
  • Parts of a COMPRESSIONAL WAVE

Compression
Rarefaction
Wavelength
28
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