E-Resources for Effective Teaching of Doppler Effect
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Wednesday, 09 September 2009 20:07 - Last Updated Wednesday, 09 September 2009 20:16
3. E-RESOURCES FOR EFFECTIVE TEACHING OF “DOPPLER EFFECT”
Abhang
bhang95@yahoo.co.in
Ranjana
a
Doppler Effect (DE) prevails in various situations-from siren on moving cars/train whistle to
sonic boom of airplanes to cosmic redshift. The topic is usually a part of physics syllabus at +2
level (Junior college). Some e-resources to make it interesting follow
physics.msuiit.edu.ph/.../spvm2006presentations/Doppler%20effect.pptSite of Western Mindanao State University, Philippines, has a powerpoint presentationby
Angelourd T. et al. After the statement, DE is explained for 4 situations 1) Source (S) &
Observer (O) both stationary; 2) S stationary, O moving 3) S moving & O stationary 4) S & O
both moving. In each case diagrams and formulae are given for 2 directions of motion-Away &
Towards. http://msowww.anu.edu.au/~pfrancis/roleplay/MysteryPlanet/doppler.ppt#339,11,Example
Australian National University (ANU)
gives apowerpoint presentationon application of Doppler Effect in Astronomy. The
background information about importance and uses of spectroscopy in Astronomy,
electromagnetic spectrum, spectrograph etc. is followed by a colored graph showing the effect
of motion of distant object (star) on
colour in
the
spectrum
with a
pplications in deducing the direction of motion of stars, radar, speed traps
http://www.walter-fendt.de/ph14e/dopplereff.htm
An animation by Walter Fendt shows that as an ambulance with a siren approaches / goes
away from the observer, the wavefronts reach the person in shorter /longer intervals
respectively.
http://www.learnerstv.com/animation/animation.php?ani=189&cat=physics
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E-Resources for Effective Teaching of Doppler Effect
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Learners TV site shows animation by D.M.Harrison (2007). Wave fronts of a moving source
depend upon observer’s position & change as speed of source is varied- speed of wave is
constant
http://www.learnerstv.com/animation/animation.php?ani=190&cat=physics
Learners TV site shows a series of 8 animated scenes by D.M.Harrison (2003): DE for moving
sound source (car); Process of hearing sound; Graphs of Source (Tuning fork) amplitude &
Detector (ear drum) response versus sound pressure for different cases: Source stationary and
detector moving towards & away, with velocity <= sound; Detector stationary and source
moving; Formulae relating source & detector frequencies covering above cases
http://galileoandeinstein.physics.virginia.edu/more_stuff/flashlets/doppler.htm
University of Virginia site displays a flashlet by M. Fowler. A moving source emits circular
waves. The speed of source can be changed & ratio of speed of source to the speed of wave,
(i.e. the Mach number) is controlled by a slider giving shockwave for Mach number>1. The
changes are seen in the picture of wavefronts as well as in sound heard using microphone.
http://galileo.phys.virginia.edu/classes/152.mf1i.spring02/DopplerEffect.htm
Notes by M. Fowler (2008) for above flashlet contain derivations of formulae for various
combinations of motions of sound source & observer, relativistic equation for Doppler shift using
light.
http://www.lon-capa.org/~mmp/applist/doppler/d.htm
Site Ion-capa has Java applet by W. Bauer (1999) for DE visualization. By dragging the mouse,
source velocity (represented by arrow) is changed. Exact value of Mach number is displayed
numerically.
http://www.gly.uga.edu/railsback/Doppler/Doppler01a.html
University of Geogia (UGA)- Difference in pitch (sound)/ colour (light) to 2 observers on 2 sides
of a moving source.
http://www.astro.ubc.ca/~scharein/a311/Sim.html#Doppler
University of British Columbia, Canada, displays an interactive java simulation with instructions
for its working. By clicking on “Run Animation” button, waves are started. Source motion can be
disabled (ie. stationary) or enabled to be linear / circular / bounce motion; Source speed can be
changed as faster/slower/ reverse/ mach; Sound speed can be decreased /increased.
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E-Resources for Effective Teaching of Doppler Effect
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http://paws.kettering.edu/~drussell/Demos/doppler/doppler.html
Kettering University site shows an animation by D. A. Russell, for stationary observer and
moving source. Wave fronts for three cases are illustrated: V
source
<V
sound
,
V
source
=V
sound
,
V
source
>V
sound
(with Mach cone and sonic boom created by supersonic jet trainer braking sound
barrier)Frequencyshift formula, Mach no. & explanation for each case, links for applications of
DE e.g. Doppler Radar, Echocardiography, Radio Direction Finding System are given.
http://www.astro.illinois.edu/projects/data/Doppler/index.html
DATA Site of University of Illinois, illustrates the concepts of Red and Blue Shifts by color of
light waves. Intermediate steps of change in velocity of the source are followed by gradual
change in frequency and colour of waves. Formula for wavelength change for light is given.
http://www.netzmedien.de/dopplereffect/index.htmlA simulation by S. Maus & D. Roth (2002). Change in source frequency moving with constant
velocity depends on observer’s position. By moving the mouse, mouse position, elapsed time
t
and wave period
T
are displayed on a graph paper. This Applet is &quot;scriptable&quot; i.e. it can be configured
and controlled by using JavaScript methodse.g. Wave phase velocity, emitter velocity relative to
wave phase velocity, wave period and time step for numerical calculation can be varied
http://www.youtube.com
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E-Resources for Effective Teaching of Doppler Effect
Written by Administrator
Wednesday, 09 September 2009 20:07 - Last Updated Wednesday, 09 September 2009 20:16
site of You Tube presents a variety of videos with commentary.
Special points of some are cited below. Time duration (minutes seconds) given in bracket
http://www.youtube.com/watch?v=a3RfULw7aAY&amp;NR=1
“DE using Car Horn” (9”) &
http://www.youtube.com/watch?v=imoxDcn2Sgo
“DE-Fire Engine siren” (18”) by David Robert- changes in sound pitch with direction of moving
sources (away/towards observer) http://www.youtube.com/watch?v=4mUjM1qMaa8
“DE- Listener in Motion” by Pelletier Physics (25”)-changes in pitch as listener moves towards /
away from a stationary source
http://www.youtube.com/watch?v=RsiY8VdDlDQ
“DE-3D Animation” by Paulie(4’:42”) Basic relations between pitch, frequency & wavelength;
Applications e.g. Doppler Radar
http://www.youtube.com/watch?v=-t63xYSgmKE
“SLight” (2’:33”) DE for Sound (Car) and Light (Star) both- sources receding / approaching
observers
:
change in pitch & colour
http://www.youtube.com/watch?v=n4BHA1hHjDc&amp;feature=related
“Red and Blue shifts of light” (12”) seen by an observer in receding /approaching parts of a
rotating galaxy.
http://www.youtube.com/watch?v=FhfnqboacV0
“What is Redshift”-Tom Jarrett of IPAC Caltech (2’:30”): Use of DE to measure distances of
stars in the expanding universe.
http://www.youtube.com/watch?v=Man9ulEYSgk
–“Red Shift” by fizzics organization (2’)-Examples of water, sound & light waves, cosmic red
shift in spectra, Big bang theory http://journal.lapen.org.mx/jan08/LAJPE-125Final%20Gimenez.pdf
site has an article
by Marcos H. Giménez et al (2008)
in Latin American Journal on Physics Education showing animation process of
the space-time visualization explains DE, Sound barrier etc.
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E-Resources for Effective Teaching of Doppler Effect
Written by Administrator
Wednesday, 09 September 2009 20:07 - Last Updated Wednesday, 09 September 2009 20:16
Thus e-resources bring life and interactivity to the concepts and enhance understanding.
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