Conduction, Convection and Radiation.
Thermal energy can be transferred from one place to another.
It ALWAYS moves from an area of higher energy (HOTTER) to an area of lower energy (COLDER).
REMEMBER.
Thermal energy is really a measure of the kinetic (movement) energy of the molecules in a substance. The energy is transferred along a substance, or from one to another, as the molecules vibrate, bang into each other and transfer energy.
It ALWAYS moves from an area of higher energy (HOTTER) to an area of lower energy (COLDER).
REMEMBER.
Thermal energy is really a measure of the kinetic (movement) energy of the molecules in a substance. The energy is transferred along a substance, or from one to another, as the molecules vibrate, bang into each other and transfer energy.
ConductionAs the end of the rod is heated, the atoms vibrate faster colliding with neighboring atoms, transferring energy.
In this way energy is conducted along the rod, without the atoms themselves moving along the rod. The energy is transferred, not the atoms. Conduction is the transfer of heat as a result of direct contact between rapidly moving atoms through a medium or from one medium to another, without movement of the media. Click on this link for an animation of Conduction. |
ConvectionConvection 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. 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, though they will not be as regular as suggested in the drawing. Click on this link for an animation of Convection currents. |
Videos - Very cheesy, but good main points.
Conduction Video. |
Convection Video. |
Radiation Video. |