Acoustic doppler effect at subsonic, sonic and supersonic speeds

In summary, the theory of the Doppler Effect considers the period measured by a moving observer relative to a stationary source as T=t(n)-t(n-1). This can lead to zero and negative periods in the case of sonic and supersonic motions of the observer. A zero period is associated with the fact that the moving observer receives one and the same wave crest, while a negative period is associated with a reversal in the order in which the wave crests are received. When considering an Electro-Magnetic wave moving at the speed of light, there are situations where the observer can move faster than the wave, but in empty space this is not possible.
  • #1
bernhard.rothenstein
991
1
Defining the period measured by a moving observer relative to a stationary source as
T=t(n)-t(n-1) where t(n) and t(n-1) represent the times when two successive wavecrests are received respectively, the theory of the Doppler Effect leads zero and negative periods in the case of sonic and supersonic motions of the observer. . Do you consider that a zero period is associated with the fact that the moving observer receives one and the same wave crest, a negative period being associated with a reversal in the order in which the wave crests are received.
Thanks for your answers
 
Physics news on Phys.org
  • #2
Do you consider that a zero period is associated with the fact that the moving observer receives one and the same wave crest
Yes, like you were surfing the wave.

negative period being associated with a reversal in the order in which the wave crests are received.
Yes, if you move faster than the waves.

What would happen if the wave was Electro-Magnetic and you move at c ?
I know that Einstein thougt about it, when he was a child, but I don't know the answer.
 
  • #3
alvaros said:
Yes, like you were surfing the wave.


Yes, if you move faster than the waves.

What would happen if the wave was Electro-Magnetic and you move at c ?
I know that Einstein thougt about it, when he was a child, but I don't know the answer.
Thanks. There is a situation when the e.m wave moves through a medium with u<c. In that case we can have the situations "luminal" and "superluminal" with simillar results as in the case of an acoustic wave.
But if the e.m. wave propagates through empty space then nobody can move with v>c and so Einstein's dream is not feasible.
 

What is the acoustic doppler effect?

The acoustic doppler effect is a phenomenon where the frequency of sound waves changes when the source of the sound is moving relative to the observer. This can result in a perceived change in pitch or frequency of the sound.

How does the acoustic doppler effect differ at subsonic, sonic, and supersonic speeds?

At subsonic speeds (less than the speed of sound), the doppler effect causes a decrease in frequency as the source moves away from the observer, resulting in a lower pitch sound. At sonic speeds (equal to the speed of sound), there is no change in frequency since the sound waves are already being perceived at their maximum frequency. At supersonic speeds (faster than the speed of sound), the doppler effect causes an increase in frequency as the source moves towards the observer, resulting in a higher pitch sound.

How is the acoustic doppler effect used in practical applications?

The acoustic doppler effect is used in various applications, including radar and sonar systems, where it is used to determine the speed and direction of moving objects. It is also used in medical ultrasound imaging to measure the velocity of blood flow in the body.

What factors can affect the accuracy of the acoustic doppler effect?

The accuracy of the acoustic doppler effect can be affected by various factors, such as the speed and direction of the source, the speed of sound in the medium, and any obstructions or interference in the path of the sound waves.

Are there any limitations to the acoustic doppler effect?

Yes, there are certain limitations to the acoustic doppler effect. It is most accurate when the source and observer are moving directly towards or away from each other. If the source or observer is moving at an angle, the perceived frequency shift may be different than the actual shift. Additionally, the doppler effect may not be detectable for very low or high frequency sounds.

Similar threads

  • Quantum Physics
Replies
1
Views
589
Replies
10
Views
3K
Replies
1
Views
697
  • Classical Physics
2
Replies
64
Views
5K
  • General Engineering
4
Replies
136
Views
14K
Replies
10
Views
3K
  • Mechanics
Replies
2
Views
5K
  • Special and General Relativity
Replies
5
Views
2K
  • Special and General Relativity
Replies
5
Views
736
  • Advanced Physics Homework Help
Replies
9
Views
5K
Back
Top