The wave movement that is associated with the vibration of the particles, the particle, the particle intermediaries intermediaries shake 1 round 1-moving waves, Lambda, so A move up and down motion B.
Waves to be associated with the oscillation of particles, particle intermediary medium particles vibrate at the first wave to move one car, so I wind up B A moving downward.
The waves move is related with the vibration of the vibrating medium media particles particles particles due 1 around wave is moving 1 and lamda. A moving up B moving down.