Why is the volt not identical to the full name Volta, unlike the other electrical units ohm, ampere, coulomb, tesla, weber and henry? Is there a historical explanation, was the volt introduced at a different time?

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    $\begingroup$ @Zano Please note that unit names should be written with lower case initials, as was in the first version of the post. So, volt and not Volt, etc. See the SI brochure §5.3 (pdf version): " In English, the names of units start with a lower-case letter (even when the symbol for the unit begins with a capital letter)" $\endgroup$ Jan 3, 2020 at 10:37
  • $\begingroup$ 'ampere'? really? $\endgroup$
    – Strawberry
    Jan 3, 2020 at 12:38
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    $\begingroup$ @Strawberry Yes, really: 'Ampère' is the scientist, 'ampere', the unit. $\endgroup$ Jan 3, 2020 at 13:48
  • $\begingroup$ Yep - fair enough; it's so often shortened that I forgot that the SI unit is in fact ampere! $\endgroup$
    – Strawberry
    Jan 3, 2020 at 13:50
  • $\begingroup$ @MassimoOrtolano Fair enough. The usage apparently varies, and I remember differently from when I was taught (not in English though). But is hard to argue with the official standards document :-) $\endgroup$
    – Zano
    Jan 5, 2020 at 15:44

1 Answer 1


The volt, ohm and farad were introduced by the same person, Latimer Clark, a cable engineer, in a paper in 1861. He started the tradition of naming units after scientists. He initially distorted all names: the unit names ohma, volt, galvat (from Galvani), and farad (from Faraday). In his words, he "neglected etymological rules".

In that same year, a committee of the British Association for the Advancement of Science began developing a coherent system of electrical units, the cgs system. Varley, a committee member, liked Clark's proposal, but he advocated adding a French name such as Ampere, to facilitate the international acceptance of the new units ("I should like to introduce a French name into the list. We have Germany, England and Italy represented"). For the same reason he may have pleaded for not distorting the French and German names. In addition, Varley objected to the galvat "because Galvani discovered next to nothing".

Latimer Clark adapted the unit names in his 'Elementary treatise on electrical measurement' (1868). He changed ohma to ohm, and dropped the galvat. Maxwell acknowledged Clark's practical units and their names in his 'Treatise on electricity and magnetism' (1873). In 1881, at the International Electrical Congress in Paris), two French names, ampere and coulomb, were added. The diplomacy worked, and the new system of electrical units was adopted by all countries. The only units that kept the initial name distortion were the volt and the farad.

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    $\begingroup$ It's interesting to note that Clark's "ohma" was a unit of tension (voltage), his "farad" was a unit of quantity (charge), his "galvat" was a unit of current, and his "volt" was a unit of resistance. $\endgroup$ Jan 1, 2020 at 6:39
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    $\begingroup$ I suppose it's OK to distort the English name because the work was by the British committee, which would accept its own system, but why would Varley still agree to distort the Italian name? Was Italy going to adopt the new system regardless? $\endgroup$
    – Ruslan
    Jan 2, 2020 at 20:42
  • $\begingroup$ As @Ruslan said, why is consistency important for France and Germany, but not Italy? $\endgroup$ May 30, 2022 at 16:45

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