What does the law of refraction state?

The law of refraction, also known as Snell's Law, tells us how light behaves as it passes from one medium to another with differing densities. Specifically, it states that when light enters a medium that is denser than the previous one, it bends towards the normal line, which is an imaginary line perpendicular to the surface at the point of entry. This bending occurs because the speed of light decreases in denser materials, causing the light ray to change direction.

The concept is crucial in optics because it helps in understanding how lenses and prisms function, and it explains the phenomena we observe when light travels through various materials, such as air, water, or glass. By defining how angles change in relation to medium change, the law of refraction enables the design of optical instruments and aids in various applications in vision correction.