Light and its properties: refraction, reflection and total reflection of light
Because light travels at different speeds in different substances, light is refracted and reflected at the interface between two substances when it is directed from one substance to another. Moreover, the angle of the refracted light changes with the angle of the incident light. When the angle of the incident light reaches or exceeds a certain angle, the refracted light will disappear and all the incident light will be reflected back, which is the total reflection of light. Different substances have different refraction angles for the same wavelength of light (i.e., different substances have different refractive indices of light), and the same substances have different refraction angles for different wavelengths of light. Fiber optic communication is based on the above principle.
