Fresnel’s equations help us understand how light behaves when it encounters the boundary between two different materials, such as air and glass or water and plastic. When light hits this boundary, some of it is reflected back into the first medium, and some of it passes through into the second medium. Fresnel’s equations describe how much of the light is reflected and how much is transmitted, depending on several key factors.
These factors include the angle at which the light strikes the surface, the polarization of the light, and the optical properties (refractive indices) of the two materials. Fresnel’s equations show that reflection and transmission vary with the angle of incidence. At certain angles, especially the Brewster angle, the reflected light can be completely polarized. They also explain why total internal reflection happens when light travels from a denser to a rarer medium beyond a critical angle.
By using these equations, scientists and engineers can predict how light will behave in different optical systems. This understanding is crucial for designing lenses, coatings, fiber optics, sensors, and many other devices where control over light reflection and transmission is essential. Fresnel’s equations form a fundamental part of wave optics and are key to modern optical technology.