Snell's Law

Snell's Law describes how light changes direction when it passes from one substance to another, like air to water. When light travels from a medium with a certain speed into another medium where it moves slower or faster, it bends at an angle. Snell's Law states that the ratio of the sine of the angles of incidence (the initial angle) and refraction (the angle after the change) is constant and depends on the speeds of light in the two media. This principle helps explain why objects appear shifted or distorted when viewed through water or glass.