A light ray is incident normally (along the normal) on the boundary between two transparent media. What happens to the ray?

1. For normal incidence the angle of incidence i = 0. 2. By Snell's law, sin i / sin r = constant; with sin 0 = 0, sin r = 0, so r = 0. 3. The chapter confirms: a ray incident along the normal (i = 0) goes forward in the same direction (r = 0) and is not refracted. 4. Hence the ray continues straight, undeviated. _Source: Balbharati (Maharashtra Board) Class 10 Science & Technology, Ch 6 "Refraction of Light", p.83_