Colloque

The Mean Free Path

D. K. C. MacDonald

Membre a labase

D. K. C. MacDonald

Résumé du colloque

All "transport" phenomena in solids (electrical and thermal conductivity, thermoelectricity, etc.) are described ultimately in terms of the mean free path for scattering. Conductivity measurements essentially give the magnitude of the mean free path, and thermoelectric power its variation with energy. Size effect measurements can give very direct information about the mean free path and recent experiments in this laboratory by White and Woods have extended earlier measurements on electrical conductivity (MacDonald and Sarginson: Nature, 163, 637; 164, 920 (1949) : Proc. Roy. Soc. A 203, 223 (1950)) to thermal conductivity and promise information of considerable interest on the thermal mean free path for electrons. It is interesting to recall that the concept of the mean free path is still to a considerable extent an admission of "ignorance" in relation to a full understanding of irreversible processes.