1) 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 A) becomes narrower B) goes horizontally without any deflection C) bends downwards D) bends upwards Answer: Option DExplanation: According to snell's law, $\mu\sin\theta=Constant$ $\therefore$ $\sin\theta\propto\frac{1}{\mu}$ As μ increases ,θ decreases Hence beam will bend upward
