Convection is heat transfer by mass motion of a fluid such as air or water when the heated fluid is caused to move away from the source of heat, carrying energy with it. Convection above a hot surface occurs because hot air expands, becomes less dense, and rises (Ideal Gas Law). Hot water is likewise less dense than cold water and rises, causing convection currents which transport energy.
Convection can also lead to circulation in a liquid, as in the heating of a pot of water over a flame. Heated water expands and becomes more buoyant. Cooler, more dense water near the surface descends and patterns of circulation can be formed.
Convection is thought to play a major role in transporting energy from the center of the Sun to the surface, and in movements of the hot magma beneath the surface of the earth. The visible surface of the Sun (the photosphere) has a granular appearance with a typical dimension of a granule being 1000 kilometers.
2007-06-11 03:43:47
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answer #1
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answered by ? 6
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Convection involves either liquids or gases where the molecules are free to move about. When they are close to the hotter surface, their kinetic energy becomes higher than the average kinetic energy of the fluid and so they start moving about allowing other less energetic particles to come into their place. The more energetic particles move further and in the process of colliding with other particles transfer some of the energy to the other particles, raising their temperature and themselves cooling down in that process. This change of kinetic energy sets up movement of layers, clusters and groups of molecules from place to place and causes convection currents and facilitates transfer of heat energy till the temperature difference is reduced.
2007-06-11 02:41:36
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answer #2
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answered by Swamy 7
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Convection is the transfer of heat by passing a fluid over another object. The heat is transferred by the particles that come in contact with one another. Heat is transferred from the warmer substance to the cooler substance.
2007-06-11 02:37:54
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answer #3
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answered by yeeeehaw 5
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The answer is radiation. Convection is the movement of air or other matter moving, just think of a convection oven. The food is heated by the hot air in the oven, where radiation is electromagnetic waves, as in solar radiation (light) through space (vacuum). Conduction is using a medium to transfer energy, as in a wire. A wire is a conductor of electricity.
2016-05-17 07:36:51
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answer #4
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answered by ? 3
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Convection can only happen in fluids( liquids and gases)
-when part of the fluid is heated, it increases slightly in volume so its density decreases( since density= mass/volume , and mass is constant)
-when its density decrease, it moves upwards replacing a volume of the fluid which moves downwards as it is more denser
-this more dense fluid when heated again , moves upawards and is replaced by another amount of the fluid, creating what is know by convection currents(cycles)
- so it is a cycle of warm fluid rising and cold one falling to the source of heat.
- this happens when u heat any fluid(water in a kettle), thats the reason for difference in breeze direction at the shore during day and night, thats how air conditionare cools the air in the whole room...... etc
2007-06-11 02:37:20
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answer #5
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answered by M!z0 3
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by moving lol jk
2015-03-22 03:04:59
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answer #6
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answered by Anonymous
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