Single correct option
A mirage seen on a hot desert road is caused by
- A. dispersion of light by dust particles
- B. diffraction of light by sand grains
- C. polarisation of sunlight by the road
- D. refraction and total internal reflection of light in air layers of different density
Show answer and solution
Answer: (D) refraction and total internal reflection of light in air layers of different density
Air near the hot ground is less dense, so its refractive index is lower. Light from the sky bends away from the normal as it comes down, and at the critical angle it is totally internally reflected, so it reaches the eye as if from a pool of water. Dispersion, diffraction and polarisation do not form the apparent water surface.
Saved on this device. Sign in or create a free account to keep it on every device.