一、多普勒效应乘坐火车的人都曾体验到,当一列火车鸣笛迎面开来,会听到汽笛声非常尖;当火车从身边掠过,汽笛声立刻变得低沉了。然而,火车里的乘客却不觉得所乘火车汽笛的声调有任何变化。火车迎面开来的速度越快,汽笛声调就越高;火车离去的速度越快,汽笛声调就越低。这种现象在1842年首先由奥地利物理学家 Christian Johann Doppler 发现,并以严格的数学公式描述了这种声音频率的改变与相对运动速度间的关系,这种现象被称为多普勒效应(Doppler eff-ect)。同样原理,如果声源固定不动,某人从某处朝 First, the Doppler effect People who have taken the train have experienced that when a train whistle head-on, you can hear a very sharp whistle; when the train passed by, the whistle immediately became low. However, the passengers in the train did not feel any change in the tone of the whistle of the train. The faster the train came in front, the higher the whistle tone was; the faster the train left, the lower the whistle tone. This phenomenon was first discovered by the Austrian physicist Christian Johann Doppler in 1842 and describes in strict mathematical formulas the relationship between this change in sound frequency and the relative speed of motion, a phenomenon known as Doppler effect Doppler eff-ect). The same principle, if the sound source is stationary, someone from somewhere