On a hot summer night, the refractive index of air is smallest near the ground and increases with he

Question

On a hot summer night, the refractive index of air is smallest near the ground and increases with height from the ground. When a light beam is directed horizontally, the Huygens' principle leads us to conclude that as it travels, the light beam\

Professor PC Thomas Classes · Answer

(b) : Consider a plane wavefront travelling horizontally.\ As refractive index of air increases with height, so speed of wavefront decreases with height. Hence, the light beam bends upwards.\