The superposition of two waves of equal amplitude, frequency and wavelength, but traveling in opposite directions. At some fixed locations in a stationary wave (anti-nodes), the two waves are in phase and added up, resulting in maximum disturbances. At some fixed locations in stationary wave (nodes), the two waves are out of phase and cancelled out resulting in minimum disturbances.

【理】驻波。可由两个振幅、波长及频率相等，但行进方向相反的波叠加而成。在驻波中某些固定的地方 (波腹)，两个波同相，因此相长，振幅最大。在另一些固定的地方 (波节)，两个波反相，因此相消，振幅最小。