| additive scalar quantity, attributed to any particle and, generally, any system of particles, to characterize its electromagnetic interactions
Note 1 to entry: Electric charge is always an integral multiple of the elementary electric charge, except for quarks. The result can be positive, negative, or zero. Owing to additivity, electric charge for any system of particles is exactly equal to the sum of their charges.
Note 2 to entry: Electric charge is subject to a conservation law. It is invariant under Lorentz transformation, and thus not dependent on the choice of a reference frame.
Note 3 to entry: Electric charges obey Coulomb's law.
Note 4 to entry: The electric current through a surface is the time derivative of the electric charge transferred through that surface.
Note 5 to entry: A charged capacitor is not an electrically charged body carrying a positive or negative electric charge. For this reason, the electric charge is defined in circuit theory as the time integral of the electric current at a terminal (see IEV 131-12-11).
Note 6 to entry: The term "quantity of electricity" is deprecated for this concept. In the IEV it is used only in relation to electrolytic devices, such as secondary cells and batteries (see, for example, IEV 482-03-14).
Note 7 to entry: The coherent SI unit of electric charge is coulomb, C. The unit ampere hour is used for electrolytic devices, such as storage batteries: 1 A·h = 3,6 kC.
Note 8 to entry: To denote the charge of a point object, symbol q is often used.