We can also calculate the refractive index of materials if we know the angles of incidence and refraction, in our experiment above the angle of incidence was 37° and the angle of refraction was 23°

where “i” is the angle of incidence in degrees, and “r” is the angle of refraction. In our experimental case we can approximate the refractive index of the Perspex used as:



Snell's law (also known as Snell–Descartes law and the law of refraction) is a formula used to describe the relationship between the angles of incidence and refraction, when referring to light or other waves passing through a boundary between two different isotropic media, such as water, glass, or air.