Wave

A wave is a travelling disturbance: it carries energy from one place to another. The water is the medium, the material through which the ripples travel. To describe a wave, distinguish the direction the wave travels from the direction in which a point of the medium moves as the wave passes.

A wave begins when a source produces a disturbance. For example, moving one end of a stretched spring gives its first coil energy and displaces it from its equilibrium position. That coil interacts with the next coil, which interacts with the next, so the disturbance travels along the spring.

A wave carries a disturbance and transfers energy. To describe its type, compare the direction in which the wave travels with the direction in which something vibrates. In a spring, it is the coils that vibrate; in a sound wave through air, it is the air particles.

A wave is a regular disturbance that transfers energy in its direction of travel without transferring matter overall. A mechanical wave passes through a medium, such as water, air or a rope. Parts of that medium oscillate about their equilibrium positions and pass the disturbance to neighbouring parts; they do not travel all the way from the source to the receiver.