Statcoulomb


The statcoulomb or franklin or electrostatic unit of charge is the physical unit for electrical charge used in the esu-cgs and Gaussian units. It is a derived unit given by
It can be converted using
The SI unit of charge is the coulomb. The conversion between C and statC is:
The number is 10 times the value of the speed of light expressed in meters/second or, in other words, the speed of light in decimeters per second.

Definition and relation to cgs base units

The statcoulomb is defined as follows: if two stationary objects each carry a charge of 1 statC and are apart, they will electrically repel each other with a force of 1 dyne. This repulsion is governed by Coulomb's law, which in the Gaussian-cgs system states:
where F is the force, q1 and q2 are the two charges, and r is the distance between the charges.
In SI units, the parallel statement for the force between two charges is:
where ε0 is the electric constant. The effect of the Gaussian-cgs definition is to fold the "1/4πε0" factor into the definition of the statcoulomb by setting it equal to unity in terms of length, mass, and time; which results in the Gaussian unit of electric charge possessing the cgs dimensions of L3/2 M1/2 T−1.