What phenomenon describes the bending of a wave as it passes from one medium to another?

The phenomenon that describes the bending of a wave as it passes from one medium to another is refraction. This occurs because waves travel at different speeds in different media. When a wave enters a new medium at an angle, its speed changes, which causes it to change direction.

For instance, when light waves travel from air (a less dense medium) into water (a denser medium), they slow down and bend towards the normal line (an imaginary line that is perpendicular to the surface at the point of entry). This effect is responsible for various optical phenomena such as the apparent bending of a straw in a glass of water.

Understanding refraction is crucial in optics and helps explain how lenses work in glasses, cameras, and microscopes, where manipulating the bending of light waves is necessary for focusing images. The other options pertain to different wave behaviors; for example, reflection involves bouncing off a surface, while diffraction refers to the spreading out of waves as they pass through a narrow opening or around obstacles. Interference involves the interaction of two or more waves resulting in a new wave pattern.