Snell’s Law can be used to calculate the angle of refraction by comparing how light bends as it moves from one medium to another with different optical densities. When light enters a new medium, its speed changes depending on the refractive index of each material. Snell’s Law relates the angle at which light hits the boundary (angle of incidence) to the angle at which it bends (angle of refraction).
To determine the angle of refraction, one needs to know:
- The angle of incidence (the angle the light ray makes with the normal in the first medium),
- The refractive index of the first medium,
- The refractive index of the second medium.
If light moves from air into glass, for example, the refractive index of air is lower than that of glass, so the light bends toward the normal. If light moves from glass into air, it bends away from the normal.
Snell’s Law helps in tracing the path of light in lenses, prisms, water surfaces, and other transparent objects. By using known values of refractive indices and the incident angle, the exact direction of the refracted ray can be predicted, which is crucial in designing optical instruments.