Thermal Conduction | Physics for GCSE/IGCSE - Year 11 PDF Download

Thermal Conduction in Solids

• Conduction is the primary method of thermal energy transfer in solids.
• It occurs when two solids of different temperatures come in contact, transferring thermal energy from the hotter object to the cooler one.
• Metals are exceptional thermal conductors due to their high number of free electrons.
• This characteristic enables them to effectively transfer thermal energy.

• Conduction occurs through two mechanisms: atomic vibrations and free electron collisions.
  • Atomic vibrations: Atoms in a solid vibrate as they are heated, transferring energy.
  • Free electron collisions: Electrons move and collide, also transferring energy.
• Heating a substance leads to increased movement (vibration) of its atoms or ions.
  • Atoms situated in the hotter portion of the solid exhibit greater vibrational motion compared to those in the cooler section.
  • This heightened motion results in collisions between atoms, facilitating the transfer of energy from one atom to another.
  • Through these collisions, internal energy is passed along until the substance reaches a state of thermal equilibrium.
  • This process is universal, occurring in all types of solids, regardless of whether they are metals or non-metals.

Thermal Conduction in Liquids & Gases

• Thermal conduction requires particles to be in proximity so that vibrations can propagate.
• Fluids, however, don't facilitate this process efficiently.
  • In liquids, although particles are close, they slide past each other instead of transmitting vibrations.
  • Gases, with widely spaced particles, lack the capacity to nudge each other effectively.
• Consequently, both types of fluids, liquids, and gases, exhibit poor heat conductivity.

Relative Thermal Conductivity

• Metals are typically known as conductors.
  • Enhanced thermal conductivity is attributed to materials possessing delocalized electrons, facilitating efficient energy transfer.
  • Consequently, there exists a broad spectrum of thermal conductivity among materials.