Which term describes the phenomenon when light is bent as it moves from one medium to another?

The phenomenon of light bending as it transitions from one medium to another is known as refraction. This occurs due to a change in the speed of light as it enters a different medium, such as from air into water or glass. When light travels through different materials, each with their own optical density, it changes speed and thus changes direction.

Refraction can be observed in various everyday scenarios, such as when a straw appears bent when placed in a glass of water. The extent of this bending can be described by Snell's law, which quantifies the relationship between the angles of incidence and refraction and the indices of refraction of the two media involved.

This concept is essential for understanding various applications, including lenses in glasses, cameras, and various optical instruments. In contrast, other options like diffraction refers to the bending of waves around obstacles or through openings, reflection involves the bouncing back of light from surfaces, and dispersion relates to the separation of light into its constituent colors. Each of these phenomena operates under different principles and conditions, highlighting the unique nature of refraction.