The Doppler Effect (in general)

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SUMMARY

The Doppler Effect describes how the observed frequency of a wave changes due to the relative motion between the source and the observer. As an object approaches, the observed frequency increases, peaking at the moment of closest approach, and then decreases as the object recedes. This phenomenon is not linear; the rate of frequency change is greatest when the source is nearest to the observer. The intensity of sound also increases as the source approaches and decreases as it moves away, confirming that the observed frequency is influenced by the changing relative velocity throughout the object's trajectory.

PREREQUISITES
  • Understanding of wave mechanics
  • Familiarity with the concept of relative velocity
  • Basic knowledge of sound propagation
  • Awareness of non-relativistic Doppler Effect principles
NEXT STEPS
  • Study the mathematical formulation of the Doppler Effect for sound waves
  • Explore the differences between the Doppler Effect in sound and light
  • Investigate real-world applications of the Doppler Effect in radar and astronomy
  • Learn about the impact of observer motion on wave frequency perception
USEFUL FOR

Students of physics, audio engineers, and professionals in fields involving wave mechanics, such as acoustics and astronomy, will benefit from this discussion on the Doppler Effect.

  • #61
I wasn't talking about the 'radial' or 'transverse' direction----we can have these components of relative velocity whatever direction(north,south,east) the motion is in.

I was actually referring to the importance of 'position' of source and observer in the analysis.Besides,as long as we know the relative velocity,and the direction of it,it doesn't matter whether it's north or south,what matters is the direction w.r.t each other (moving towards or moving away)--we can choose north-south directions as we please.

The line I'm referring to is on the page given below,in the third last paragraph of the section 'Analysis'.

http://en.wikipedia.org/wiki/Doppler_effect
 
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  • #62
Time reversal?Iwould wwant to know more on it
 
  • #63
Urmi Roy said:
I wasn't talking about the 'radial' or 'transverse' direction----we can have these components of relative velocity whatever direction(north,south,east) the motion is in.

I was actually referring to the importance of 'position' of source and observer in the analysis.Besides,as long as we know the relative velocity,and the direction of it,it doesn't matter whether it's north or south,what matters is the direction w.r.t each other (moving towards or moving away)--we can choose north-south directions as we please.

The line I'm referring to is on the page given below,in the third last paragraph of the section 'Analysis'.

http://en.wikipedia.org/wiki/Doppler_effect
That wiki paragraph is referring to the fact that in a more complete analysis one must take the travel time of the signal into account (from source to observer) in order to determine what the observer actually observes at any given time. To do that requires knowing the position of the source at the time of emission, not just its direction of motion.
 
  • #64
Thanks,Doc Al,I understand now.
 
  • #65
Waves farther from the source lag behind those closer to it.So if you have positive radial velocity greater than the speed of sound you hear the song played backwards
That's time reversal
 

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