In physics, the phenomenon where light bends as it passes through different mediums is known as refraction. This bending occurs due to a change in the speed of light when it transitions between materials with different optical densities. Refraction is responsible for various optical effects, such as the distortion of objects viewed through water or the formation of rainbows when light passes through raindrops. The degree of bending can be calculated using Snell's law, establishing the relationship between the angles of incidence and refraction.