How does thermal conduction occur in solids?

Thermal conduction in solids occurs through the vibration of atoms and the movement of free electrons.

In more detail, thermal conduction is the process by which heat energy is transferred within a body due to the kinetic energy of its particles. In solids, this process is facilitated by the close proximity of the particles. The particles in a solid are tightly packed together and are constantly vibrating. When heat is applied to a solid, the particles at the heat source vibrate more rapidly. These vibrations are then transferred to the neighbouring particles.

This transfer of kinetic energy from one particle to another continues throughout the solid, causing the heat to spread. This is often referred to as a 'domino effect'. The rate at which this happens depends on the type of solid. Metals, for example, are good conductors of heat because they have free electrons. These free electrons move rapidly and randomly within the metal, colliding with other electrons and atoms, thereby transferring kinetic energy and spreading the heat more quickly.

In contrast, in non-metals, heat conduction is slower because they lack these free electrons. Instead, the heat is transferred solely through the vibrations of the atoms. This is why materials like wood or plastic are considered poor conductors or good insulators.

It's also important to note that the rate of thermal conduction in solids can be affected by other factors such as temperature gradient, cross-sectional area, and the length of the path that the heat energy has to travel. The greater the temperature difference, the faster the rate of heat transfer. Similarly, a larger cross-sectional area or a shorter path length can also increase the rate of heat transfer.