Question

Explain briefly how mirage is formed

plz be fast

Answer 1

Mirage is an optical illusion where it appears that water has converted on the road at the distant place but when we go there, we cant find any water.
This is due to the variable refractive index as medium and total internal reflection.
Explanation: 
1. Density of airincreases with height. refractive index of air increases with density and also with height.
2. When the light from tall object like tree or from sky passes through a medium, it suffers refraction and takes a curved path because of total internal reflection.
3. The refracted light from sky is reflected from the ground for the observer.
4. Hence the observer feels the water being present on the road which is virtual image of the sky