Paschen's law
(also Paschen law)
noun
A law relating to gas discharges formulated by Paschen in 1889 (Ann. der Physik u. Chemical 37 90) which states that at a constant temperature the breakdown voltage in any particular gas depends only on the product of the pressure and the interelectrode distance.
Origin
Early 20th century; earliest use found in Proceedings of the Royal Society of London.