by on October 11, 2020
ATMOSPHERIC   WATER VAPOURS There are different terms that describe  water vapour in the atmosphere. Dew Mist Cloud Humidity     Read more about PHYSICS for High Schools
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by on October 11, 2020
Humidity Humidity generally describes the quantity of water vapour available in the air. Dry air has a very low quantity of water vapour while wet or humid air has high quantity of water vapour. When human body sweats in a dry air, the sweat evaporates faster than when the air is damp and contain plenty of water vapour.  Humid air is a wet air while non humid air is a dry air. Relative humidity. Relative Humidity can be defined as the ratio of the mass of water vapour  present in a v...
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by on October 11, 2020
Cloud When you are in Aeroplane at high altitude and you look down through the side screen, you can hardly see the ground. This is because of the cloud in the air , high above the ground. Cloud forms when the temperature of air falls below dew point. Cloud is a mass of small water droplet that floats in the air, high up in the atmosphere.     Read more about PHYSICS for High Schools
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by on October 11, 2020
Mist When wind blows a warm moist air over a cold surface , the sudden lowering of the temperature causes the moisture to condense at a temperature below dew point. Also during harmattan , moist air near the Earth surface cooled down . the water vapour in the air condenses and form droplet which are suspended in the air. This is known as Mist. Mist are formed when the air cooled below dew point. It restrict visibility and is closer to the ground . Whenever there is mist, you can only...
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by on October 11, 2020
Dew When air containing water vapour is cooled , it is possible to reach a temperature at which the water present in the air saturated it. If this air is cooled further , droplet of water will condense on cold surface . This is called Dew. The temperature at which this happen is called dew point Dew point can be defined as the temperature at which the water present in the air is enough to saturate the air. This resulted in dew, anytime air is cooled below its dew point.     Rea...
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by on October 11, 2020
Vapour Pressure During the process of evaporation, molecules escape from the surface of liquids in an enclosed container. These molecules accumulate on the surface of the liquid to form vapour. The pressure exacted by this escaped molecules or vapour on the surface of the liquid is called vapour pressure of the liquid. Vapour Pressure  is defined as the pressure exacted by the escaped molecules or vapour on the surface of the liquid ..   Saturated and unsaturated vapour Saturat...
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by on October 11, 2020
SUBLIMATION Sublimation is the process where by solid changes to vapour without going through liquid state. An iodine crystal changes to vapour when placed in a test-tube at room temperature without first change into liquid. Also dry ice() , when left in the open air , changes directly to vapour without passing through liquid state. This process is called Sublimation       Read more about PHYSICS for High Schools
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by on October 11, 2020
Molecular Explanation of Evaporation Each of the molecules of a liquid does not have the same temperature and energy but the liquid as a whole has its average temperature. The molecules with high energy tends to escape through the surface of the liquid . when this happen through evaporation the resultant energy of the remaining molecules  become lower  than the previous value. This resulted in a lower temperature of the liquid. The human body utilises the process of evaporation for cooling...
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by on October 11, 2020
Boiling Point  and Condensation The boiling point of a liquid is the temperature at which the liquid changes to vapour . The reverse of boiling is condensation . The temperature at which liquid changes to vapour is the same with the temperature at which the vapour changes back to liquid. When heat is applied to a liquid the temperature increases . As the temperature increases bubbles of vapour appear in the liquid. These process is called boiling.     Effect Of Impurities And P...
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by on October 11, 2020
The refrigerator The principle of evaporation causes cooling is used in refrigerator . The components of refrigerator are: Compressor  (Pump) Evaporator Expansion valve Vent   Ammonia evaporates inside a coiled copper tube surrounding the freezing compartment . As the ammonia evaporates in these coils, the ammonia absorbs heat from the surroundings air, thus cooling the inside of the refrigerator and its contents. The vapour is circulated through the pump (compressor) ...
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by on October 11, 2020
Evaporation Some  volatile liquids , for example, Petrol and Alcohol changes from its liquid state to gaseous state without application of heat. The molecules of the liquid gradually escape from the surfaces of the liquid causing the liquid to change to its vapour form. This process is called evaporation. Evaporation can be defined as a process whereby liquid changes to vapour .   Factors affecting evaporation of liquids. The following factors affect evaporation of liquids P...
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by on October 11, 2020
Melting Point And Freezing Point There are three state of matter Solid  Liquid  Gas Matter can change from one state to another. When heat is applied to solid , its temperature rises, until when it reaches a peculiar temperature, the solid begins to melt into its liquid form. This temperature is the melting point of the solid.   The melting point can be defined as the temperature at which solid changes to its liquid state. The melting point of a solid is the same as th...
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