点波源的机械波 (如球面波、水面波 )在介质中传播时 ,即使不计介质对能量的吸收 ,波的振幅也随位置的变化而发生改变 .本文以 2 0 0 2年高考上海物理卷第4题为例 ,对波的振幅作一些讨论 ,原题如下 :原题　如图 1所示 ,S1、S2 是振动完全相同的两图 1个机械波的波源 ,振幅为 A, When the point wave source’s mechanical wave (such as spherical wave, water surface wave) propagates in the medium, even if the energy absorbed by the medium is not counted, the amplitude of the wave will also change with the change of position. This paper takes the Shanghai physical examination in the 2002 college entrance examination. For example, the 4 questions, some of the wave amplitude discussion, the original question is as follows: the original title shown in Figure 1, S1, S2 is exactly the same vibration of the two waves of a mechanical wave, the amplitude is A,