Question

how does the water kept in an earthan pot remain cool

Answer 1

In an earthen pot, water gets evaporated quickly through the pores. Cooling is caused by evaporation. Some heat energy is utilised during the process of evaporation. Since this energy is taken from the water itself, it leads to a lowering of temperature in the remaining amount of water.

Answer 2

This is because of evaporation. When a liquid changes to a gaseous (or vapour) state without boiling, it is known as evaporation.

The earthen pot is made of mud and has many minute pores (extremely small holes). Through these pores that the water, placed inside the earthen pot oozes out. Now, to evaporate, the water needs to absorb heat, which will change it to vapour.

The only way the water oozing out of the earthen pot can turn to vapour is by absorbing heat from the liquid within the earthen pot and the earthen pot itself. Due to this process of continuous absorption of heat from the water inside the matka, in a few hours, this water becomes cool