Radiation, Convection and Conduction?

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Offline The Scientist

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Radiation, Convection and Conduction?
« on: 09/02/2011 07:32:23 »
Can anyone please explain the difference in these three terms using layman terms. I am confused with what they are and their purposes. Please help. Thanks lots!
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Offline Soul Surfer

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Radiation, Convection and Conduction?
« Reply #1 on: 09/02/2011 08:55:07 »
They are basically the three main method that heat energy can be transferred through and between bulk materials as seen in the laboratory.  Conduction involves the diffusion of the heat through a solid liquid or gaseous material purely through the contact and interaction of their molecules.  hot molecules jiggle more violently than cold ones and when in contact this jostling is transferred between them.  Convection involves the transfer of energy by the movement of the molecules themselves therefore it only applies to liquid or gaseous materials where the molecules can move.  This happens essentially because hotter molecules take more space and are therefore less dense and when in a gravitational field will tend to rise.  Note gravitation is essential for convection to take place.  Radiation occurs when the energy is transferred by the emission and absorption of electromagnetic radiation from one part of the material to another and there is no physical contact or movement of the material.  this is the sort of heat we feel from the sun.   Consider this experiment with a hot domestic central heating "radiator".  Radiation is the heat we feel on the back of our hand while standing a meter away from the radiator, convection is the heat we feel when holding our hand 30 cm above the radiator.  conduction is the heat we feel when touching the radiator.
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Offline yor_on

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Radiation, Convection and Conduction?
« Reply #2 on: 09/02/2011 19:53:57 »
Very sweet explanation SoulSurfer, especially the later part where you gave a actual way to do a hands on experiment. That made it very visual.
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