Conduction, Convection & Electrons

304 Words2 Pages
The molecules of gas have a comparatively large space between them. Conduction occurs only in solids which have closely packed molecules whose motion is restricted to vibration in the same position within the solid mass. The addition of heat energy, due to this compactness, is translated to Kinetic Energy (greater vibrational motion) which is immediately transferred to neighbouring molecules and the Heat Transfer by Conduction is Achieved. Conduction is the fastest form of Heat transfer. Convection, heat transfer in fluids (Liquids and Gases) is due to rising currents of fluid due to decrease in Density. Cooler fluid moves in to replace the rising current of fluid. This too, is heated and rises and a circulatory motion is set up within the Fluid. Radiation, the slowest of the Heat Transfer processes will only heat substances 'or bodies" in the direct path of the Heat Rays. Stand in front of a fire on a cold night. Your front will become warm while you back remains cold. The Sun or an Open fire transfers heat in this manner by Direct Heat Rays (Radiated Heat). Radiation will also travel through a vacuum (as with the heat from the Sun), whereas, conduction and convection will not. These same principles of Conduction apply also to flow of Electricity as in the flow of Electrons. The electrons in piece of metal can leave their atoms and move about in the metal as free electrons. The parts of the metal atoms left behind are now charged metal ions. The ions are packed closely together and they vibrate continually. The hotter the metal, the more kinetic energy these vibrations have. This kinetic energy is transferred from hot parts of the metal to cooler parts by the free electrons. These move through the structure of the metal, colliding with ions as they
Open Document