Maddy, Carole, and Maria are enjoying a day at the beach. They are body surfing and playing on their boards. Imagine that wave A catches up with wave B. Describe the change, if any, in wave amplitude.

When the two waves meet, there are two possibilities:

1. If the waves were both in phase and moving in the same direction, then, the amplitude will double, this is called constructive interference.

2. If the two waves were exactly out of phase, then they will try to move the water surface in all directions, thus, no movement and the waves cancel out. This is called destructive interference.