Snell’s Law states that light changes direction when changing speed.

The refractive index of a material is how quickly light moves through it—light goes its maximum speed only in a vacuum. This is an important notion when considering a lens as the angle of incidence (angle at which light strikes the surface) is further modified by the refractive index. The speed of light in a material depends on the wavelength, so different wavelengths will bend differently. This is the driving force behind chromatic aberration.rK3

  1. Caleb Kruse, “Focusing on Blue - 10 Projects,” accessed August 10, 2022, (See notes.)