简谐波的图象是一条正弦或者余弦曲线,由波的图象判断波的传播方向,质点的振动方向是本章知识的难点。判断的方法有多种,比较简单直观的方法是直接在波形图上画箭头确定。具体方法是在波图上该质点处沿波的传播方向或者质点的振动方向画一个箭头,再在过该点的波形同侧画另一个 The image of a harmonic wave is a sine or cosine curve. The propagation direction of the wave is judged by the image of the wave. The vibration direction of the particle is a difficult point in the knowledge of this chapter. There are many ways to judge, and the simple and intuitive method is to determine the arrow directly on the waveform diagram. The specific method is to draw an arrow along the propagation direction of the wave or the vibration direction of the particle at the mass point on the wave diagram, and draw another one on the same side of the waveform passing the point.