Angle of refraction
= Angle of refraction
{title2=$\theta_t$}
The <angle of refraction> is the <angle> between the transmitted <light ray> and the surface <normal vector>, measured on the transmitted side. With positive <refractive indices>, a propagating transmitted <light ray> satisfies $n_i\sin\theta_i=n_t\sin\theta_t$ in <Snell's law>. The incident and transmitted <angles> are measured from the same normal line, not from the surface and not from the emergent <light ray> at a second surface.