The Volta effect as a cause of static electrification

An experimental investigation of the static electrification of metal/metal surfaces shows that the erratic results normally obtained are owing to there being more than one cause, and that the complete elimination of rubbing leaves an effect that is amenable to quantitative measurement. This ‘separation charging’ is shown to be related to the contact potential, and to have the characteristics to be expected if the Volta-Helmholz hypothesis of its origin is correct. The importance of this explanation of tribo-electrification has long been debated. The supposition that the hypothesis predicts negligible charging of conductor/conductor surfaces is shown to be based on an inadequate understanding of the significance of surface topography at the points of contact. By paying proper attention to this, and revising the hypothesis to allow for the transfer of electrons by tunnel effect, a precise theory of separation charging is derived. When applied to the experiments, agreement within the limits of experimental error is obtained, without the introduction of disposable constants.

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