Doppler Effect apparent change in frequency of a wave due to the motion of the source of the wave If the object is moving towards the observer the frequency will appear to increase If the object is moving away from the observer the frequency will appear to decrease ID: 529061
Download Presentation The PPT/PDF document "Doppler Effect, Bow Waves, and Shock Wav..." is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
Doppler Effect, Bow Waves, and Shock WavesSlide2
Doppler Effect
~apparent change in frequency of a wave due to the motion of the source of the wave.
If the object is moving towards the observer the frequency will appear to increase
If the object is moving away from the observer the frequency will appear to decreaseSlide3
Why does this happen
Frequency- number of waves to pass by in a second.
Waves travel out from their source in rings, like when a stone is thrown in a pond.
This person should have the same number of waves hitting them each second
As this person
Will.Slide4
But if the source is moving
Each new wave will start in a different place than the last wave.
This person now has less waves hitting them each second
than this person
Will.
. . . . . . . .
Each dot shows the
where the source was
when that wave was
madeSlide5
Observable traits of frequency
Sound frequency is observed as the pitch.
High frequency high pitch (dentist drill), low frequency low pitch (bass drum)
Light frequency is color
Low freq- Red OYGBI violet- high freq
Moving towards
Moving away fromSlide6
With Light…
It causes red shift (moving away from you) and blue shift (moving towards you) in stars.
But with out an
extremely
high speed it is not noticeable to the human eye
You need sensitive equipment to notice a frequency change
Like Dual Doppler XL or Doppler 2000 With this radar you can check the motion of a storm Slide7
What if an object is moving faster than the waves they are producing
The front edge of the
New wave will be
Ahead of the last
Wave!
It also creates
This pattern
Of strong
Waves at the
edges
here
And here
By strong I mean
Larger amplitude
A whole bunch of waves
Hit at once causing constructive interferenceSlide8
Where does this occur
Two dimensionally this is called a
Bow Wave
.
It commonly occurs on a speed boat
Three dimensionally this is called a Shock Wave.It occurs in supersonic jets (ones that go faster than the speed of sound)When that strong wave hits you, you hear a
sonic boom (all of the sound hitting you at once)Slide9
Sound Barrier
There is an actual “barrier” to moving at the speed sound.
When you hit the speed of sound (or any wave you are making) you hit all of those waves you just made.
All of that interference causes a turbulence.
This goes away if you are moving faster than sound.
A sonic boom is heard by observers whenever an object moves faster than sound not just when it crosses the threshold