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Energy is defined via work, so the SI unit of energy is the same as the unit of work – the joule (J), named in honour of James Prescott Joule [1] and his experiments on the mechanical equivalent of heat. In slightly more fundamental terms, 1 joule is equal to 1 newton metre and, in terms of SI base units
Symbol [1] Name of quantity Unit name Symbol Base units E energy: joule: J = C⋅V = W⋅s kg⋅m 2 ⋅s −2: Q electric charge: coulomb: C A⋅s I electric current: ampere
This is the definition declared in the modern International System of Units in 1960. [13] The definition of the joule as J = kg⋅m 2 ⋅s −2 has remained unchanged since 1946, but the joule as a derived unit has inherited changes in the definitions of the second (in 1960 and 1967), the metre (in 1983) and the kilogram . [14]
The ampere is named for French physicist and mathematician André-Marie Ampère (1775–1836), who studied electromagnetism and laid the foundation of electrodynamics.In recognition of Ampère's contributions to the creation of modern electrical science, an international convention, signed at the 1881 International Exposition of Electricity, established the ampere as a standard unit of ...
ampere: A electric current "The ampere, symbol A, is the SI unit of electric current. It is defined by taking the fixed numerical value of the elementary charge e to be 1.602 176 634 × 10 −19 when expressed in the unit C, which is equal to A s, where the second is defined in terms of ∆ν Cs." [1]
Diagram of original Ampere experiment. The form of Ampere's force law commonly given was derived by James Clerk Maxwell in 1873 and is one of several expressions consistent with the original experiments of André-Marie Ampère and Carl Friedrich Gauss.
By definition, the change in electrostatic potential energy, U E, of a point charge q that has moved from the reference position r ref to position r in the presence of an electric field E is the negative of the work done by the electrostatic force to bring it from the reference position r ref to that position r.
André-Marie Ampère (UK: / ˈ æ m p ɛər /, US: / ˈ æ m p ɪər /; [1] French: [ɑ̃dʁe maʁi ɑ̃pɛʁ]; 20 January 1775 – 10 June 1836) [2] was a French physicist and mathematician who was one of the founders of the science of classical electromagnetism, which he referred to as electrodynamics.