Thermal Fluctuations in Conductors

Abstract

In this paper we investigate the behavior of a conductor in thermal equilibrium with the surrounding radiation field. We obtain an expression connecting the spectrum of the current fluctuations with the absorption. For small frequencies this reduces to Nyquist's relation. For large frequencies, however, the relation is quite different; namely, the current fluctuations are proportional to the (skin) resistance and depend also on the shape of the conductor.