Difference Between Doppler Effect in Sound and Light

Thekey difference between doppler effect in sound and light is in their velocity.对于声音中的多普勒效应，观察者和来源的速度相对于波浪经过的介质很重要，而对于光线效应，只有观察者和源之间的速度相对差异很重要。

Doppler effect or Doppler shift is the change infrequency of a waverelative to an observer who is moving relative to the wave source. This effect was named after the physicist Christian Doppler. The major reason for the Doppler effect to occur is the emission of each successive wave crest from a position closer to the observer (compared to the crest of the previous wave) when the source of the waves is moving towards the observer. This makes each wave take slightly less time to reach the observer compared to the previous wave. Therefore, the time taken by the arrivals of successive wave crests at the observer’s end reduces, increasing the frequency. This leads to the waves bunching together.

内容

1.Overview and Key Difference
2.什么是声音中的多普勒效应
3.What is Doppler Effect in Light
4.多普勒在声音与表格中的多普勒效应以表格形式
5.Summary – Doppler Effect in Sound vs Light

什么是声音中的多普勒效应？

Doppler effect in sound is the change in the frequency of the sound observed by an observer due to the velocity of the observer and the source of the sound, which are relative to the medium in which the sound passes through. Sound waves cannot pass through vacuums; the sound requires a medium to pass through. Therefore, the velocity of the wave of sound through the medium we are using (usually air surrounding us) affects the Doppler effect.

通常，声源和接收器相对于介质的速度相对低于介质中声波的速度。因此，我们可以使用以下方程进行计算。

f是频率(观察),f0发出吗ted frequency, c is the speed of waves in the medium, vr is the speed of observer relative to the medium, and vs is the speed of sound source relative to the medium.

There are several applications of the doppler effect of sound, including acoustic Doppler current profiler, siren, medical applications such as echocardiograms, Leslie speaker, etc.

What is Doppler Effect in Light?

在光中，多普勒效应是由于观察者和光源之间的相对运动，观察者观察者观察到的光频率的明显变化。光是一种电磁波that does not require a medium to pass through. Therefore, we can consider that light is passing through a vacuum. For the waves passing through a vacuum, the Doppler effect depends only on the relative speed of the observer and the light source.

例如，我们可以描述redshift and blue shiftusing the Doppler effect. When considering visible light, when the light source is moving away from the observer, it causes the frequency received by the observer to be lower than the frequency transmitted by the light source. This is named the redshift. Moreover, if the light source moves towards the observer, the frequency received by the observer becomes greater than the transmitted frequency. Then the frequency of light shifts towards the high-frequency end of the visible light range, which leads to the blue shift.

多普勒在声音和光中有什么区别？

Sound waves propagate through a medium while light does not require a medium to pass through. Therefore, the key difference between doppler effect in sound and light is that for the doppler effect in sound, the velocity of the observer and the source are relative to the medium in which the waves go through are important, whereas for the doppler effect in light, only the relative difference in velocity between the observer and the source are important.

The below infographic lists the difference between doppler effect in sound and light in tabular form.

Summary – Doppler Effect in Sound vs Light

Sound waves propagate through a medium, while light does not require a medium to pass through. Therefore, for the doppler effect in sound, the velocity of the observer and the source are relative to the medium in which the waves go through are important, whereas for the doppler effect in light, only the relative difference in velocity between the observer and the source are important. Thus, this is the key difference between doppler effect in sound and light.

Reference:

1. Millis, John P. “What is Blueshift?” thowsco。

Image Courtesy:

1.“”Velocity0 70c”：(CC BY-SA 3.0)via Commons Wikimedia