Thursday, September 4, 2008
CHAPTER 8! / 2:55 AM
TRANSFER OF THERMAL ENERGY:)*Thermal energy always flow from a region of higher temperature to a region of lower temperature.
*Thermal energy is transferred by any of these three processes:Conduction,Convection and Radiation.
*Transfer of thermal energy takes place when there is a temperature difference.
CONDUCTION.
[this transfer of thermal energy through a medium,without the medium moving is called conduction.]
-conduction is the process of thermal energy transfer without any flow of the material medium.
REMINDER:liquids and gases are poor conductors of heat.
CONVECTION.
-Another process of thermal energy transfer is convection.
-Convection is the transfer of thermal energy by means of currents in a fluid(liquids or gases)
RADIATION.
-Radiation does not require a medium for energy transfer.
-Radiation is the continual emission of infrared waves from the surface of all bodies,transmitted without the aid of medium.
[factors affecting rate of infrared radiation:colour and texture of the surface;surface temperature and surface area.]
common applications of convection:electric kettles;household hot water system;air conditioners and even refrigerators.common applications of radiation:teapots;the greenhouse;vacuum flasks.
