Doppler Effect

[medstu2006]

1. When the source is moving towards a standing observer, the frequency and intensity increases. However, when the source is moving with constant velocity towards the observer, the intensity increases, but the frequency remains the same. Can someone please explain these 2 opposing statements? I cannot make the connection.

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[DrChandy]

1. When the source is moving towards a standing observer, the frequency and intensity increases. However, when the source is moving with constant velocity towards the observer, the intensity increases, but the frequency remains the same. Can someone please explain these 2 opposing statements? I cannot make the connection.

Your confusion between the two statements arises from the way the word "increases" is interpreted in the two different situations.

For a given source approaching an observer,

If the source is approaching at constant velocity towards the stationary observer, the perceived frequency is increased relative to the actual frequency, but this perceived higher frequency is constant.

If the source is approaching at an accelerating pace towards the stationary observer, the frequency is perceived to be continuously increasing.

Good luck.

 

[NapeSpikes]

Your confusion between the two statements arises from the way the word "increases" is interpreted in the two different situations.

For a given source approaching an observer,

If the source is approaching at constant velocity towards the stationary observer, the perceived frequency is increased relative to the actual frequency, but this perceived higher frequency is constant.

If the source is approaching at an accelerating pace towards the stationary observer, the frequency is perceived to be continuously increasing.

Good luck.