coulomb

SI coherent derived unit with special name and symbol

Name	Symbol	Quantity	Base units
coulomb	C	electric charge	s A
The coulomb, symbol C, is the SI coherent derived unit of electric charge. It is the special name for the ampere second, symbol s A. One coulomb is the charge transported by a constant current of one ampere in one second.
Definition			e
$1 \mspace{4mu} \text{C} \mspace{6mu} = \dfrac{1}{1.602 \mspace{4mu} 176 \mspace{4mu} 634 \times 10^{-19}} \mspace{6mu} e\\ \\ \\ 1 \mspace{4mu} \text{C} \mspace{6mu} \approx 6.241 \mspace{4mu} 509 \mspace{4mu} 074 \mspace{4mu} 460 \mspace{4mu} 762 \mspace{4mu} 608 \times10^{18} \mspace{6mu} e$

The coulomb is named after the French physicist, Charles-Augustin de Coulomb (1736 – 1806).

The fixed numerical value of the elementary charge, e, is defined as 1.602 176 634 × 10⁻¹⁹ C. This definition implies the exact relation e = 1.602 176 634 × 10⁻¹⁹ C. Inverting this relation gives an exact expression for the coulomb in terms of the defining constant e:

$e \mspace{19mu} = 1.602\ 176\ 634 \times 10^{-19} \ \text{C}\\ \\ \\ 1 \ \text{C} = \dfrac{e}{1.602\ 176\ 634 \times 10^{-19}}$

The effect of this definition is that one coulomb is exactly ¹⁄_{(1.602 176 634 × 10⁻¹⁹)} of the value of the elementary charge, e.

Capacitance

One coulomb is the amount of excess charge on a capacitor of one farad charged to a potential difference of one volt.