Thermal Conduction (Cambridge (CIE) O Level Physics): Revision Note

Thermal Conduction in Solids

• Conduction is the main method of thermal energy transfer in solids

• Conduction occurs:

When two solids of different temperatures come in contact with one another, thermal energy is transferred from the hotter object to the cooler object

• Metals are the best thermal conductors

  • This is because they have a high number of free electrons

Thermal Conduction in a Metal

Conduction: the atoms in a solid vibrate and bump into each other

• Conduction can occur through two mechanisms:

  • Atomic vibrations

  • Free electron collisions

• When a substance is heated, the atoms, or ions, start to move around (vibrate) more

  • The atoms and ions at the hotter end of the solid will vibrate more than the atoms and ions at the cooler end

  • As they do so they bump into each other, transferring energy from atom to atom

  • These collisions transfer internal energy until the whole substance is at the same temperature

  • This occurs in all solids, metals and non-metals alike

• When free electrons are also present, such as in a metal:

  • The free electrons at the hotter end of the solid vibrate more

  • They bump into other atoms and ions, transferring energy

  • This speeds up the process of thermal conduction

  • Hence, metals are good thermal conductors