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Conduction


Thermal energy is energy transferring from a hotter place to a colder place - in other words from a higher temperature to a lower temperature. Thermal energy requires a temperature difference if it is to be transferred. 

Conduction of heat energy takes place mainly in solids.


We can explain the transfer of heat energy through a solid by thinking of the heat from the source as 

causing the atoms of the solid to vibrate and gain kinetic energy.

 

These atoms cause neighboring atoms to vibrate. Kinetic energy is transferred from one atom to the 

next. Heat energy is conducted through the solid in  this way. As the atoms of the solid gain 

kinetic energy the temperature of the  solid increases. The heat transfer continues until the two objects 

have reached thermal equilibrium and are at the same temperature.





In liquids and gases (fluids) heat energy is transferred mainly by a process called convection.



Are some materials better conductors than others?


YouTube Video


Both metals and non metals conduct heat. Metals are generally are much better conductors than non-metals. 

1- Conduction in Non-metals:

Imagine a long glass rod, one end is being heated, the other end is cold. There is thus a temperature 

difference between the two ends. At the hot end of the rod atom are vibrating a lot . At the cold end they 

are vibrating much less. As they vibrate the atoms collide with their neighbours. This process results in 

each atom sharing its energy with its its neighbouring atoms. Atoms with a lot of energy end up with 

less and those with a little end up with more. The collision gradually transfers the energy from the 

atoms at the hot end to those at the cold end.




2- Conduction in metals:
Metals are good conductors for another reason. In a metal there are particles called electrons that can move about freely. Electrons are smaller than atoms, and they are the particles that carry energy when an electric current flows through a metal. They also carry energy when heat is transferred through a metal.


And there are some metals conduct electricity than others.

You can check that from this interactive link.


http://www.boardworks.co.uk/media/adb0fe14/GCSE%20Science%20Sample/Particles_and_energy_Four_Rods.swf

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