How is Snell’s Law mathematically expressed?

Snell’s Law describes how light bends when it passes from one transparent material to another, such as from air into water or from glass into air. It states that the amount of bending depends on the angle at which the light hits the surface and the refractive indices of the two materials. If light travels from a medium with a lower refractive index to one with a higher refractive index, it slows down and bends toward the normal (an imaginary line perpendicular to the surface). If it goes from a higher to a lower refractive index, it speeds up and bends away from the normal. This predictable relationship helps in designing lenses, prisms, and optical devices.