The propagation velocity of electromagnetic waves in free space, an idealized standard reference state ( like absolute zero for temperature ), is conventionally denoted by c < sub > 0 </ sub >:< ref > With ISO 31-5, NIST and the BIPM have adopted the notation c < sub > 0 </ sub >.</ ref >

* ISO 31-5

Notable developments in this century include the work of Georg Ohm, who in 1827 quantified the relationship between the electric current and potential difference in a conductor, Michael Faraday, the discoverer of electromagnetic induction in 1831, and James Clerk Maxwell, who in 1873 published a unified theory of electricity and magnetism in his treatise Electricity and Magnetism.

Electricity would remain little more than an intellectual curiosity for millennia until 1600, when the English scientist William Gilbert made a careful study of electricity and magnetism, distinguishing the lodestone effect from static electricity produced by rubbing amber.

Electricity and magnetism ( and light ) were definitively linked by James Clerk Maxwell, in particular in his " On Physical Lines of Force " in 1861 and 1862.

Electricity, magnetism, and motion: A self-taught Vermonter pointed the direction for lighting the world.

* Self-taught English mathematician George Green publishes An Essay on the Application of Mathematical Analysis to the Theories of Electricity and Magnetism in Nottingham, the first mathematical theory of electricity and magnetism, introducing a version of Green's theorem, the idea of potential theory, and the concept of what will come to be called Green's functions.

* Electricity and magnetism

* Electricity and magnetism.