The light hitting an object's surface, not that reflected or scattered from it. The wavelength of incident light is usually more varied than that reflected from a surface, determining the colors perceived in the object. It undergoes selective absorption of some wavelengths as it is reflected. The law of reflection is a principle that when light is reflected from a smooth surface, the angle of incidence ? the angle at which the light hits a surface ? is equal to the angle of reflection, and the incident ray, the reflected ray, and the normal to the surface all lie in the same plane.Also see additive, mirror, optical mixing, primary colors, and subtractive.