Transferring of thermal energy from hot end to cold end by molecular vibration is quite slow. Another much faster mechanism of thermal energy transfer is, free electrons diffusion. Solids can either be metals or non-metals. Solids which are metal have free electrons which are not possessed by non-metals. When thermal energy is supplied, besides the transfer of heat energy through vibrating molecules, these free electrons also gain kinetic energy. These fast moving electrons then diffuse / spread into the cold end of the metal. They collide with the atoms in the cooler parts of the metal and transfer their kinetic energies to them.
A good conductor is a kind of material with more free electrons, because thermal energy can be transferred more quickly. All metals are therefore good conductor.
The rate of heat transfer determines whether an object is a good/ poor conductor.
Monday, June 15, 2009
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