Thermal conduction (diffusion)

Thermal conduction (or diffusion) is the transfer of heat (internal energy) by microscopic collisions of particles and movement of electrons, that takes place in a solid, liquid, or aeriform medium (inside a single body or two bodies in contact with each other).

Heat transmission occurs naturally from the higher temperature zones to those with lower temperatures. Thermal energy manifests itself at the microscopic level as the oscillation of the molecules of material; this oscillation increases with increasing thermal energy accumulated in the body (i.e., increases with temperature).

The oscillations of each molecule caused by the stored thermal energy occur around the position initially occupied by the molecule, so that in a given interval of time the average position of the molecules is always the same, so that in thermal conduction there is no transport of matter, but the only transmission of molecular collisions.