驻波的瞬时能流密度

INSTANTANEOUS ENERGY FLUX DENSITY OF STANDING WAVE

本文首先指出了人们利用瞬时能流密度解释驻波能量的认识误区。之后论证了两列简谐波在相遇区域任一点的瞬时能流密度等于两列波各自的瞬时能流密度之和的条件是两列波必须相向传播,从而严格证明了驻波瞬时能流密度的结论。最后从受力的角度分析了驻波的能量只能在相邻波腹和波节间流动。

Firstly, we point out the misunderstanding of people, who use the instantaneous energy flux density to explain the energy of standing wave. Then we strictly prove that the instantaneous energy flux density of two harmonic waves at arbitrary point in the crossed region is equal to the sum of the two corresponding instantaneous energy flux densities if and only if the two waves are travelling oppositely. Thus, the conclusion of instantaneous energy flux density of standing wave is strictly proved. At last, by using the force analysis, we explain the energy of standing wave can only be transited between the adjacent wave loop and wave node.