Conduction | Physics for Grade 10 PDF Download

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
    
    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 at the hotter end of the solid will vibrate more than the atoms 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 thermal equilibrium is achieved throughout the substance
    • This occurs in all solids, metals and non-metals alike

Thermal Conduction in Liquids & Gases

• For thermal conduction to occur the particles need to be close together so that when they vibrate the vibrations are passed along
  • This does not happen easily in fluids 
  • In liquids particles are close, but slide past each other
• In gases particles are widely spread apart and will not 'nudge' each other
• Both types of fluid, liquids and gases, are poor conductors of heat

Relative Thermal Conductivity

• Conductors tend to be metals
  • Better thermal conductors are those with delocalised electrons which can easily transfer energy
  • This means that there is a wide range of thermal conductivity
    
    Different materials have different rates of conductivity