Waves

1
Waves

• Rhythmic disturbance carries energy through
  matter or space
• I.e.
• - water waves
• - sound waves
• - mechanical waves

2
Wave Pulses

• A wave with a sudden disturbance or distortion
  that travels through a material or medium.

3
Examples of Wave Pulses
4
Continuous Waves

• A regularly repeating sequence of wave pulses

5
Oscillations and Wave Motions

• Up Down Back Forth Circular
  
  Movement Movement Movements

6
Waves

• A wave is an energy transport phenomenon
• Meaning as a disturbance moves through a medium
  from one particle to its adjacent particle,
  energy is being transported from one end of the
  medium to the other without transporting matter.

7
Waves Cont.

• There is no overall single motion of the medium
  through which the wave travels.

8
Example

• You and your partner hold one end of a slinky.
• When you give the coil a back and forth motion a
  disturbance in the coil travels throughout the
  slinky transporting energy.

9
Example Cont.

• The energy continues through the slinky until it
  arrives at the end of the slinky, in which your
  partner would feel the energy as it reaches their
  end.

10
TRANSVERSE WAVES

• A wave in which particles of the medium move in a
  direction perpendicular to the direction which
  the wave moves
• Movement Moves at right angles toward the
  direction of the wave. The energy is transported
  from left to right. As this happens the
  individual coils of the medium will be displaced
  upwards and downwards. The waves are a succession
  of crests and troughs.

11
Examples of Transverse Waves

• -Ripples in Water

12
Examples of Transverse Waves

• -Vibrations of Stretched String

13
Examples of Transverse Waves

• -Light Waves

14
Examples of Transverse Waves

• Radio Waves

15
Longitudinal Waves

• - A wave in which particles of the medium move in
  a direction parallel to the direction which the
  wave moves.
• Movement Travel back and forth in the same
  direction as the wave motion so the disturbance
  takes place in the direction of the propagation
  (wave.) As the energy is transported from left to
  right, the individual coils of the medium will be
  displaced leftwards and rightwards.

16
Examples of Longitudinal Waves

• -SOUND WAVES

17
Summary
18
Travelling Waves in Two Dimensions

• These are waves that move in more than one
  dimension.
• Ex Waves that occur in a pond after a rock is
  dropped in it

19
Wave Fronts (crests)

• The rings that are formed where the water
  molecules have a maximum displacements upwards,
  move around where the stone is dropped
• At 90o angle to rays

20
Rays

• The line showing the direction that the wave is
  moving in.

21
Bibliography

• http//www.vasa.abo.fi/vos/vosusers/tillman/4.doc
• http//www.school-for-champions.com/science/wavepu
  lse.htm
• http//www.school-for-champions.com/science/waves.
  htm
• Glencoe Physics Principles and Problems.
  Zitzewitz, Paul W. pg. 312
• http//hyperphysics.phy-astr.gsu.edu/hbase/sound/t
  ralon.html
• http//www.glenbrook.k12.il.us/gbssci/Phys/Class/w
  aves/u10l1c.html
• http//www.gmi.edu/drussell/Demos/waves/wavemotio
  n.html

22
Wave Characteristics

• Margaux Polillo
• Eva Schwartz
• Jordan Stopak-Behr

23
Amplitude is the maximum positive displacement
from the undisturbed position of the medium to
the top of a crest.
http//id.mind.net/zona/mstm/physics/waves/partsO
fAWave/waveParts.htmamplitude
24
Frequency refers to how many waves are made per
time interval. This is usually described as how
many waves are made per second, or as cycles per
second.
The bottom waves have higher frequencies than the
top red one.
25
The section of the wave that rises above the
undisturbed position is called the crest. That
section which lies below the undisturbed position
is called the trough.
26
The wavelength of a wave is the distance between
any two adjacent corresponding locations on the
wave train. This distance is usually measured in
one of three ways crest to next crest, trough to
next trough, or from the start of a wave cycle to
the next starting point.
27

• Displacement is a vector quantity which refers to
  "how far out of place an object is" it is the
  object's change in position.

Period refers to the time which it takes to do
something The period of a wave is the time for
a particle on a medium to make one complete
vibrational cycle
28
Compression- the wave is pushed
together Rarefaction- the wave is This takes
place in Longitudinal waves, Example a slinky A
slinky Just sitting at rest- compression you let
it go then the compression travels across the
wave Transverse waves do not have either
rarefaction or compression
29
Speed of a wave the distance which a point on a
wave (such as a compression or a rarefaction)
travels per unit of time, it is often expressed
in units of meters/second (abbreviated m/s).
http//www.glenbrook.k12.il.us/GBSSCI/PHYS/CLASS/s
ound/u11l2c.html
30
Graphical Representations

• Transverse and Longitudinal Waves

• Displacement-Position Graphs
• Displacement-Time Graphs

31

• Displacement-Position Graphs
• Transverse Waves

• Transverse Waves
• Definition oscillates perpendicular
• this graph a picture of the wave at a given
  instant
• in time
• X-axis position along the medium
• Y-axis
• Positive displacement of the medium in one
  direction
• Negative displacement of the medium in the
  opposite direction
• Example imagine a rope
• at rest the rope will form a straight line along
  the x-axis
• Moving and then frozen at a given instant the
  rope will form this picture

32

• Displacement-Position Graphs Longitudinal Waves

• Longitudinal waves
• Definition oscillates parallel
• Not a picture Graphical representation of each
  particles movement
• X-axis position along the medium
• Y-axis
• Positive displacement of particles to the right
• Negative Displacement of particles to the left

• Example imagine a slinky
• At rest all the loops are equally spaced
• so the graphical representation is a straight
  line
• Moving some of the loops have moved toward each
  other (y) and some away (-y)

33

• Displacement-Time Graphs
• Transverse Waves and
• Longitudinal Waves

• Both Transverse Waves and Longitudinal Waves
• x-axis time
• y-axis displacement of one point in the medium
• Can determine T (period) and f (frequency)
• NOT ? (wavelength)

34
Displacement-Time GraphsTransverse vs.
Longitudinal

• Longitudinal Waves
• Graphical Representation of a point at every
  instant in time
• Example imagine a slinky with a loop marked in
  orange
• Follow the orange loop with your eye your eye
  will oscillate back and forth
• y movement right
• -y movement left

• Transverse Waves
• Picture of a point taken at every instant in time
• Example imagine a rope marked at a given point
  in red
• Follow the red mark with your eye your eye will
  trace the curve of the graph

35
How Is Wave Speed Found?

• Wave Speed f x ?
• But that is very similar to vd/t

36
How Is It Similar?

• frequency 1/TPeriod (T) the time it takes
  for
• one full wave to be completed.
• ? wavelength the distance
• covered by one full wave. The
• distance from one crest to the next.

37
Therefore

• Velocity (a.k.a. Wave speed) distance covered
  by one full wave (a.k.a. Wave length) x 1 / the
  time of one wave.
• In other words
• Wave Speed Wavelength x frequency
  
• Is the same as
• Velocity distance / time

38
Reflection, Refraction and Transmission of Waves

• Ransom Livingston, Chelsea Cooper, India Hayes,
  Katie Brown, Chavis Amber, Khim Khue

39
Huygens principle

• Every point on a wave-front may be considered a
  source of secondary spherical wavelets which
  spread out in the forward direction at the speed
  of light. The new wave-front is the tangential
  surface to all of these secondary wavelets.

40
Huygens Principle
41
Angle of Incidence Angle of Reflection
(Huygens' Principle)
Advancing waves are the start of new waves and
every point on the old wave is reflected on the
new wave.

• New waves are always at a 90 to the original
  wave.

42
Refraction
43
(No Transcript)
44
(No Transcript)
45
Huygens law and Snells law

• Snells law for air
• For air and water
• The Huygen wavelets gets slower at the medium
  where the n1 index of refraction (air) into
  water n2

46
Ratio of Speeds in substances

• Diamond 2.419 Ethyl Alcohol 1.361
• Cubic Zirconia  2.21 Ice1.309 Glass(flint)1.66
  Water  1.333
• Glass (crown)1.52 Air 1.000

47
Bibliography

• http//www.mathpages.com/home/kmath242/kmath242.ht
  m
• http//www.physlink.com/Education/AskExperts/ae471
  .cfm
• http//id.mind.net/zona/mstm/physics/waves/propag
  ation/huygens1.html
• http//farside.ph.utexas.edu/teaching/302l/lecture
  s/node135.html
• http//www.pas.rochester.edu/tipton/huygens.pdf
• http//sol.sci.uop.edu/jfalward/refraction/refrac
  tion.html
• http//www.saburchill.com/physics/chapters2/0011.h
  tml

48
Wave Diffraction and Interference
49
Diffraction of Waves by Apertures

• The Diffraction of the waves are only truly
  noticeable when the size of the aperture (gap)
  are approximately the same size as the wavelength.

50
Diffraction of Waves Around Obstacles

• Where there is no obstacle, the waves continues
  on. Where the obstacle is met, the portion of
  the wave at the edge bends around the obstacle.

Larger wavelength, more noticeable diffraction
around obstacle
51
Diffraction

• CD / DVD
• Act as diffraction grading, moving the angle of
  the lasers reflection to convey the data on the
  disk.

52
Diffraction

• Rainbows
• The light diffracts off the water particles,
  acting as a diffraction grading, creating the
  rainbow of color one sees.

53
Superposition

• Two or more waves travel through same medium
• The waves just move through each other

http//www.kettering.edu/drussell/Demos/superposi
tion/superposition.html
54
Constructive and Destructive Interference

• Constructive- two or more waves hit each other
  and their amplitudes add together to create one
  big amplitude.
• Destructive- two or more waves hit each other and
  create a lesser amplitude.

http//www.kettering.edu/drussell/Demos/superposi
tion/superposition.html
55
Superposition

• http//www2.biglobe.ne.jp/norimari/science/JavaEd
  /e-wave2.html

56
Phase 1
57
Phase 2
58
Phase 3
59
Phase 4
60
Example Question
61
Example Answer
62
Sources

• http//www.launc.tased.edu.au/online/sciences/phys
  ics/diffrac.html
• http//physics.usc.edu/bars/135/LectureNotes/Ligh
  tWaves.html
• http//www.walter-fendt.de/ph11e/huygenspr.htm
• http//www2.biglobe.ne.jp/norimari/science/JavaEd
  /e-wave2.html

63
The Doppler Effect Light and sound

• AuSha Washington

64
Explanation

• Discovered by Christian Doppler
• the change in frequency and wavelength of a
  wave that is perceived by an observer moving
  relative to the source of the waves.

65
Sound- Explanation

• If the source of the waves and the receiver are
  approaching each other the, frequency of the
  waves will increase and the wavelength will be
  shortened resulting in a higher pitched sound.
• A source approaches and moves closer during
  period of the sound wave so the effective
  wavelength is shortened, giving a higher pitch
  since the velocity of the wave is unchanged
  resulting in a shortened pitch

66
Sound- Example

• You hear the high pitch of the siren of the
  approaching police car, and notice that its pitch
  drops suddenly as the police car passes you.

67
Sound- Example
You hear the high pitch of the siren of the
approaching ambulance, and notice that its pitch
drops suddenly as the ambulance passes you.

• Another example is the sudden drop in the pitch
  of a train whistle as the train passes a
  stationary listener.

68
Light-Explanation

• The amount of color shift is bigger if the
  emitting object is moving faster.
• If the object is coming toward you, the light is
  shifted toward shorter wavelengths, blue shifted.
  
• If the object is going away from you, the light
  is shifted toward longer wavelengths, red
  shifted.
• Blue shifted higher frequency higher pitch.
• Red shifted lower frequency lower pitch.

69
Light-Example

• For a star approaching Earth, increasing
  frequency makes the light appear bluer. This is
  known as a blueshift.
• If a star is moving away from Earth, decreasing
  frequency makes the light appear redder, which is
  known as a redshift.
• By measuring the extent of the change in color,
  an observer can also gauge how fast the star is
  moving the faster it moves, the more pronounced
  the color shift will be.

70
Radio Waves and Astronomy

• The Doppler effect in reflected radio waves is
  used to sense the velocity of an object under
  surveillance. In astronomy, the Doppler effect
  for light is used to measure the velocity,
  distance, and rotation of stars and galaxies
  along the direction of sight.

71
Interesting Facts

• Doppler effect for radio waves is utilized by
  astronomers to determine the velocities of dust
  clouds in the spiral arms of the Milky Way
  galaxy.
• The discovery of red shifts in the spectra of
  galaxies in the 1920s led Edwin Hubble to
  conclude that the universe is expanding.
• First direct proof that our own galaxy is
  rotating. The Doppler shift in radar pulses
  reflected from the surfaces of Venus and Mercury
  have been analyzed to obtain new values for their
  periods of rotation
• Echocardiography is a medical test using
  ultrasound and Doppler techniques to visualize
  the structure of the heart.

72

• http//www.teachersdomain.org/resources/phy03/sci/
  phys/energy/doppler/index.html
• http//www.kettering.edu/drussell/Demos/doppler/d
  oppler.html
• http//en.wikipedia.org/wiki/Doppler_effect
• http//www.astronomynotes.com/light/s10.htm
• http//archive.ncsa.uiuc.edu/Cyberia/Bima/doppler.
  html

73

• http//www.glenbrook.k12.il.us/GBSSCI/PHYS/CLASS/w
  aves/u10l3d.html
• http//exoplanets.org/doppframe.html

74
Standing Waves

• Carolyn Foster
• Tim Menuhe

75
Standing Wave

• Is a wave that stays in a constant position
• This occurs when waves are moving in opposing
  directions
• Examples
• Fast flowing rivers
• Transmission lines

76
Standing Waves in One Dimension

• Standing Waves will be either
• Open ended
• Closed at both Ends
• Orone end open, one end closed
• (See Chalk Board)

77
Standing Waves vs. Traveling Waves

• Standing waves stay in a constant position going
  up and down
• Traveling Waves travel, continuing theyre up
  and down motion to the right and left