Question

With respect to atmospheric refraction which of the following point distinguish between cold air and hot air?
a) Cold air is denser than hot air
b) Hot air is lighter than cold air
c) Cold air have higher refractive index than hot air
d) All of these

Answer 1

ANSWER

Hot air is lighter than cool air and hence is less dense. It has refractive index slightly less than that of cool air. Since the physical conditions of the refracting medium (air) are not stationary, the apparent position of the object seems to fluctuate when seen through hot air. This wavering is an effect of atmospheric refraction. Atmosphere is a heterogenous mixture of different particles thus it does not have a constant refractive index. Refraction occurs when the refractive index of a substance changes. Thus atmospheric refraction occurs in a medium of gradually changing refractive index.

Answer 2

With respect to atmospheric refraction, (d) All of these points distinguish between cold air and hot air.

Explanation:

• Atmospheric refraction is the deviation of light from a straight line as it passes through the atmosphere due to the variation in density of the air.
• Cold air is denser that hot air that is, hot air is lighter than cold air because molecules of hot air have more heat energy which enables them to expand faster and rise up making it lighter as compared to cold air.

• Since, cold air has more density, it will increase the refractive index of the cold air that is, light will travel slower through it.

Hence, With respect to atmospheric refraction, (d) All of these points distinguish between cold air and hot air.