Explain giving examples the various factors on which rate of evaporation depends.
The rate of evaporation depends on the following factors:
(1) Surface area: If the surface area is increased the rate of evaporation also increases.
(a) To dry the clothes we spread them to dry faster.
(b) Tea in saucer cools faster than in a cup.
(2) Temperature: If the temperature is increased the rate of evaporation also increases. Due to increase in temperature the particles gain more kinetic energy and change their phase from liquid to gaseous. Water will evaporate faster in sun than in shade.
(3) Humidity: It is the amount of water vapour present in air. The air can hold definite amount of water vapour, at a given temperature. If the amount of water vapour is high in the air then the rate of evaporation decreases.
On hot and humid day, desert coolers are not effective as the air cannot hold anymore moisture to get the cooling effect.
(4) Wind speed: With the increase in wind speed, the rate of evaporation increases.
The particles of water vapour move away with the wind, decreasing the amount of water vapour in the surrounding.