What is the term for the change in direction of waves as they pass through different media?

The term that describes the change in direction of waves as they pass through different media is refraction. This phenomenon occurs because waves travel at different speeds in different materials. When a wave enters a medium where its speed is different—like from air to water—it bends at the boundary due to the change in speed.

Refraction is most commonly observed with light waves, but it can occur with any type of wave, including sound and water waves. The amount of bending depends on the angle at which the wave hits the boundary between the two media and the relative speeds of the wave in each medium.

This process is vital in many practical applications, such as the functioning of lenses in glasses and cameras, where precise bending of light is necessary to focus images clearly. Understanding refraction not only helps explain natural phenomena, such as the bending of a straw when placed in a glass of water, but also underpins many technological advances in optics and acoustics.