The law of refraction, also known as Snell’s Law, describes how light bends when it passes from one medium into another with a different refractive index (a measure of how much a material slows down light).
It states that:
- When light travels from one transparent medium to another (like from air to water), its speed changes, which causes the light to change direction, or refract.
- The amount of bending depends on the refractive indices of the two media and the angle at which the light enters the new medium.
Key points of Snell’s Law:
- If light enters a denser medium (higher refractive index), it slows down and bends toward the normal.
- If light enters a less dense medium (lower refractive index), it speeds up and bends away from the normal.
- The incident ray, the refracted ray, and the normal all lie in the same plane.
Snell’s Law is essential in understanding how lenses, prisms, rainbows, and fiber optics work.