The Heat developed during the Absorption of Electricity by Metals

Abstract

IN 1901 (O. W. Richardson, Camb. Phil. Proc., vol. xi., p. 286) one of the present writers showed that the phenomena attending the emission of negative electricity by hot metals could be explained on the assumption that the electrons which, on the electron theory of metallic conduction, move freely inside the metal attain sufficient kinetic energy at high temperatures to enable them to overcome the forces tending to keep them inside the surface and so escape. From the way in which the thermionic current varied with the temperature of the metal it was shown that the difference in the value of the potential energy of an electron when outside and when inside a metal could be calculated. Somewhat later (O. W. Richardson, Phil. Trans., A, vol. cci., p. 497) it was shown that the existence of this difference in the potential energies would involve a loss of thermal energy by the substance when the electrons were being given off, and it was pointed out that this effect would increase very rapidly with the temperature, so that at sufficiently high temperatures the loss of energy due to this cause would be greater than that arising from thermal radiation. An effect of this character has recently been discovered by Wehnelt and Jentzsch (Ann. der Physik, iv., vol. xxviii., p. 537).