Final answer:
Snell's Law explains the bending of light as it moves between mediums of different densities, modeling the change in angle due to the change in speed, with the formula n₁ sin θ₁ = n₂ sin θ₂.
Step-by-step explanation:
Snell's Law, also known as the law of refraction, deals with the bending of light as it passes from one medium into another where its speed changes. When light enters a denser medium, it slows down and bends towards the normal—a line perpendicular to the interface between the media.
The mathematical expression for Snell's law is n₁ sin θ₁ = n₂ sin θ₂, where n₁ and n₂ are the refractive indices of the first and second media, respectively, and θ₁ and θ₂ are the respective angles of incidence and refraction. The law derives from applying Huygens's principle, which models wavefronts at the boundary and explains the light's behavioral change due to varying propagation speeds in different media. The smaller the speed of light in the second medium, the more significantly the light ray changes direction, thus demonstrating refraction.