Question

Water in an earthen pitcher gets cooled due to:
A) The slower rate of evaporation
B) The faster rate of evaporation
C) No evaporation at all
D) Some unknown reason

Answer 1

Hint: Evaporation has a cooling effect on a body. When a liquid evaporates from a surface, it takes heat from the surface to aid in evaporation, thereby making the surface cooler.

Complete step by step answer:
Earthen pitchers have small holes in them since they are made of clay, which inherently has air pores in its structural features. Thus, water kept in an earthen pitcher can seep through the pores and reach up to the outer surface of the pitcher.
Evaporation has a cooling effect on the body. When a liquid evaporates from a surface, it takes heat from the surface to aid in evaporation, thereby making the surface cooler.
After reaching the surface the water from the pores takes heat from the pitcher to evaporate, thereby cooling the pitcher and the water inside it. Also, the pores allow for good ventilation and the passage of air from the outside to the inside of the pitcher. This also has a part in keeping the water inside the pitcher cool.
All of this aids excellently in the process of evaporation and cooling the water inside the pitcher.
Thus, the correct answer is B) Faster rate of evaporation.
Additional information: In summer, we wear cotton clothes for the same reason. Cotton clothes have very small holes in their fibers. So, they allow the sweat from our body to evaporate quickly and cool our bodies.

Note: A simple experiment to get a feel for the cooling effect of evaporation is to splash water on your face and then to stand under a fan. You will instantly feel cool on your face since the wind from the fan aids in evaporation which in turn has a cooling effect.