What are the highest and lowest parts of a wave called?

The highest part of a wave is referred to as the crest, while the lowest part is called the trough. This terminology is commonly used in physics and represents the critical points in wave dynamics.

The crest is characterized by the maximum displacement of the wave above the equilibrium position, indicating the point where the energy of the wave is at its peak. Conversely, the trough signifies the lowest displacement point of the wave, where the energy dips to its minimum. Understanding these terms is essential in various scientific fields, including physics, engineering, and oceanography, as they describe the fundamental properties of wave behavior.

The definitions provided in the other choices do not conventionally address the terminology used in wave physics. "Valley" and "dip" are less standard in this context when specifically discussing waves, while "peak" can often be synonymous with crest but is not as universally accepted for distinguishing between the high and low points in wave terminology.