读者“相如”问:“为什么火车进站时鸣笛声的音调会变高,而远离车站时音调会变低呢?”这个问题涉及波动的一个物理效应,即多普勒效应.为了回答这个问题,我们首先要明确提问中的火车是一个波源,进站时,它发出笛声,声音通过空气(介质)向四周传播.月台上站立的人是观测者,人耳接收到的笛声音调(频率)比笛声本身的音调高.1842年,奥地利物理学家多普勒发现,当波源或观测者或两者相对于传播波的介质运动时,观测者接收到的波的频率(f)与波源发出的波的频率(f_0)不同.我们称这种物理现象为多普勒效应.多普勒推导出.如果波源和观测者都相对于介 The reader asks: “Why is the tone of the whistle getting higher when the train stops, and the tone going lower when it is farther away from the station?” "The problem involves a physical effect of fluctuations, namely the Doppler In order to answer this question, we must first make it clear that the train in question is a source of waves, and when it stops, it makes a siren and the sound is spread all over the air (medium). The man standing on the platform is the observer, The tone (frequency) of the flute received was higher than the tone of the flute itself. Austrian physicist Doppler discovered in 1842 that when the wave source or observer or both were moving relative to the medium of the propagating wave, the observer received (F) is different from the frequency of the wave (f_0) from the wave source. We call this physical phenomenon Doppler effect. Doppler deduced. If both the wave source and the observer are relative to the medium