what are the the limiting speeds of observer and the sound source for Doppler's effect of sound to hold good
Answers
Doppler effect is not valid only when the source velocity is greater than that of sound. In other situations, it is valid. When the source velocity approaches the speed of sound, the subsequent waves come closer and closer together and the wavelength approaches 0. At the speed of sound, this is what happens- the source gives off a wave which travels at the speed of sound and the source follows the wave as it is moving at the same speed. This means that the next wave that it gives off is along the first wave and subsequent waves all combine and get bunched up together, moving together. So instead of even rise and fall of air pressure, you get an abrupt dramatic increase then fall in air pressure, creating a shock wave, which is the sonic boom.
Resnick Halliday (Walker version) has a good diagram for this phenomenon, in the waves chapter. Try to get hold of a copy( actual or online).
Answer:
there are some of the limiting speed size of the observer and the sound source for the Doppler effect of sound that holds good