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Thermal Agitation of Electricity in Conductors

Nature volume 119, pages 50–51 (1927)Cite this article

ORDINARY electric conductors are sources of spontaneous fluctuations of voltage which can be measured with sufficiently sensitive instruments. This property of conductors appears to be the result of thermal agitation of the electric charges in the material of the conductor.

The effect has been observed and measured for various conductors, in the form of resistance units, by means of a vacuum tube amplifier terminated in a thermocouple. It manifests itself as a part of the phenomenon which is commonly called 'tube noise.' The part of the effect originating in the resistance gives rise to a mean square voltage fluctuation V2 which is proportional to the value R of that resistance. The ratio V2/R is independent of the nature or shape of the conductor, being the same for resistances of metal wire, graphite, thin metallic films, films of drawing ink, and strong or weak electrolytes. It does, however, depend on temperature and is proportional to the absolute temperature of the resistance. This dependence on temperature demonstrates that the component of the noise which is proportional to R comes from the conductor and not from the vacuum tube.

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  1. Bell Telephone Laboratories, Inc., New York, N.Y., Nov. 17. https://www.nature.com/nature

    J. B. JOHNSON

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  1. J. B. JOHNSON
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JOHNSON, J. Thermal Agitation of Electricity in Conductors. Nature 119, 50–51 (1927). https://doi.org/10.1038/119050c0

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