Evaporation IGCSE Physics By Aadeng Apang

What is Evaporation ? Evaporation is the process in which the more energetic particles from the surface of the water turns into vapor. When the particles escape the average energy of the particles reduces and so the liquid starts to cool down. Factors affecting evaporation are: Air pressure Temperature Air Saturation

Saturation Of the Air/ humidity If the air is saturated with other substances the liquid, does not evaporate quickly due to lack of space in the air. When the humidity is 100% then the air is already saturated with water therefore there is no evaporation

Air Pressure If the air pressure is high on the surface of water then water won’t evaporate quickly. The pressure on the water doesn't allow water particles to escape quickly as vapor. e.g. storms- they are high pressure systems that does not allow evaporation to take place.

Temperature Temperature also increases the rate of evaporation. If the temperature is high then water evaporates faster. e.g. boiled water evaporates faster than just water in a glass as vapors.

Evaporation creates a cooling effect Evaporation gives a cooling effect because when the particles escape the surface of the water then the kinetic energy becomes less in the particles causing the liquid to cool down. E.g. when sweating and standing underneath a fan, the body cools down.

Bibliography https://www.boundless.com/physics/textbooks/boundless-physics- textbook/temperature-and-kinetic-theory-12/phase-changes-106/humidity- evaporation-and-boiling-385-6076/ http://www.goes- r.gov/education/comet/hydro/basic/HydrologicCycle/print_version/03- atmospheric_water.htm http://www.bbc.co.uk/schools/gcsebitesize/science/aqa/heatingandcooli ng/heatingrev5.shtml