 The conventional symbol for thermal conductivity is "k".On a microscopic scale, conduction occurs within a body considered as being stationary; this means that the kinetic and potential energies of the bulk motion of the body are separately accounted for.Internal energy diffuses as rapidly moving or vibrating atoms and molecules interact with neighbouring particles, transferring some of their microscopic kinetic and potential energies, these quantities being defined relative to the bulk of the body considered as being stationary.