What does Snell's Law describe?

Snell's Law, also known as the law of refraction, specifically describes how light bends when it passes from one medium to another with a different index of refraction. This law provides a mathematical relationship between the angles of incidence and refraction and the indices of refraction of the two media. When light travels from air into water, for example, it changes speed and direction—this phenomenon is captured mathematically by Snell's Law, which states that the ratio of the sine of the angle of incidence to the sine of the angle of refraction is constant and equal to the ratio of the indices of refraction of the two media.

Understanding Snell's Law is essential in various applications, such as optics, vision, and the design of lenses. It clarifies how and why light behaves the way it does when moving through different materials, making it a fundamental concept in the study of wave phenomena in physics.