Question

Give Reasons for the Following:
1)A desert cooler is used to keep the room cool
2)clothes dry at a slower rate on a humid day
3)wet clothes dry faster under a fan

Answer 1

Dear student ,

1. Desert cooler is a very simple device used to provide cool air during hot weather conditions. It uses water to cool the air. Three sides of the cooler are covered with a material which is kept wet using water and pump. The fourth side has blower which sucks in air from outside and delivers it inside the room. It works on a simple principle that as the hot air from outside passes through wet surface, the water evaporates, increases the moisture content of air and cools it. Hence, desert cooler provides us with cool air using a simple mechanism.

2. Things remain damp and wet, and take longer time to dry when the atmosphere around them is damp and wet. Humidity is the amount of moisture or water vapour present in air at any moment in time. On a humid day, the air is full of water vapour. As the air gets warmer, its capacity to hold the water vapour increases. As a result, conditions become more and more humid. Hence, wet clothes take longer time to dry on a humid day.

3. Clothes get dry faster under a fan because the water from the clothes which are evaporated as water vapours are pushed faster by the air and the nearby air do not saturate. Whereas on a still day the air around the clothes get saturated with water vapours as the diffusion of these vapours are really slow and clothes takes time to get dry.

Regards