The ampere was then defined as one coulomb of charge per second. The Coulomb approximation is fundamentally an empirical construct. The term formula 36 or formula 37 is known as the "Coulomb" or "electrostatic term". The understanding of friction was further developed by Charles-Augustin de Coulomb (1785). They were designed by Joseph-Marie-Blaise Coulomb. The SI unit of charge is the coulomb (C). It is named after Charles-Augustin de Coulomb. The damper operates on the principle of a coulomb damper. The distinction is important in small systems such as those showing Coulomb blockade. Vlasov suggests that these difficulties originate from the long-range character of Coulomb interaction. This may also be written using Coulomb constant . Otherwise, formula 95 where formula 96 is the classical Coulomb distance of closest approach. It is called the Coulomb barrier.