The net angular deflection experienced by a light ray after one or more refractions or reflections. The total deviation ε of a light ray can be computed, given the incidence angle α. The same calculation allows for determination of the emergence angle δ. The angle of deviation is the angle between the original incident ray and the emergent ray. Since the larger angle of deviation corresponds to a larger refractive index, violet light would emerge with the largest angle of deviation and red light would emerge with the smallest angle. The difference between the angles of deviation of any two rays is called the angle of dispersion.