What occurs to light as it travels from one material to another, causing a change in speed and potentially direction?

When light travels from one material to another, such as from air into water, it encounters a change in the medium that affects its speed. This change in speed causes the light to bend, a phenomenon known as refraction. The fundamental principle behind this is governed by Snell's Law, which relates the angle of incidence to the angle of refraction based on the refractive indices of the two materials.

Refraction is essential for understanding how lenses work and plays a crucial role in various optical applications, including camera lenses, corrective eyewear, and the design of optical instruments. By bending light as it passes through different substances, it can be manipulated to focus or disperse, creating clear images or effects.

The other options, while related to light behavior, do not describe the specific phenomenon of light bending and changing speed at the interface of two different materials.