Physics
Physics
Problem
A light ray in air is incident on a glass slab at to the normal. Beyond the glass, it enters water through a parallel face. Calculate the angle that the emergent ray makes with the normal in water. (Give your answer to the nearest degree.)Intuitive explanation
The key is recognizing that refraction happens independently at each interface, governed by Snell's law. Start by finding the angle inside the glass using the air-glass boundary, then use that refracted angle at the glass-water boundary to find the final angle in water. Since the glass faces are parallel, the ray inside the glass travels at a constant angle—you just need to track how that angle changes when crossing into the next medium.
Intuitive explanation
The key is recognizing that refraction happens independently at each interface, governed by Snell's law. Start by finding the angle inside the glass using the air-glass boundary, then use that refracted angle at the glass-water boundary to find the final angle in water. Since the glass faces are parallel, the ray inside the glass travels at a constant angle—you just need to track how that angle changes when crossing into the next medium.