On His Majesty's Service; On Her Majesty's Service.
the standard unit of electrical resistance in the International System of Units (SI), formally defined to be the electrical resistance between two points of a conductor when a constant potential difference applied between these points produces in this conductor a current of one ampere. The resistance in ohms is numerically equal to the magnitude of the potential difference. Symbol: Ω.
On Her (or His) Majesty's Service
the derived SI unit of electrical resistance; the resistance between two points on a conductor when a constant potential difference of 1 volt between them produces a current of 1 ampere Ω
Georg Simon (ˈɡeːɔrk ˈziːmɔn). 1787–1854, German physicist, who formulated the law named after him