Question

When we sit at camp fire, objects beyond the fire seen swaying. Give the reason for it. 

(OR) 

What are the reasons for the objects beyond the fire seen swaying, when we sit at camp fire?

Answer 1

• The temperature of the surrounding air changes due to convection of heat by the camp fire. 
• This leads to change in density and refractive index of air, continuously. 
• The continuous change in refractive index of air changes the refracted path of the light ray. 
• This is the cause for swaying of an object.