In the cgs system, electrical charge is a fundamental quantity defined via the electrostatic force (as will be described below); in the SI system, electrical current is fundamental and defined via the magnetric force while electrical charge is a derived quantity.
The statcoulomb is defined as follows: if two objects each carry a charge of 1 statC and are 1cm apart, they will repel each other with a force of 1 dyne. As a result, if all quantities are measured in the cgs system, then Coulomb's law describing the force F between two charges q_{1} and q_{2} a distance r apart takes the simple form
Note that in order for the above formula to work, the dimension of statcoulombs must be [mass]^{1/2} [length]^{3/2} [time]^{1}. This is different from the dimension of coulombs which accounts for the fact that the factor k mentioned above is not dimensionless.
The coulomb is an extremely large charge rarely encountered in electrostatics, while the statcoulomb is closer to everyday charges.
Search Encyclopedia

Featured Article
