ESU লেElectrostatic system unit unit is a system used to measure electrical charges , electricity , and voltage in centimeter-gram-seconds (or "CGS") metric unit systems. In electrostatic units , the electric charge is defined by the force applied to other charges. EMU: The centimeter-gram-second system has two units of electric charge: the charge electrostatic unit , the ESU , or the statcolomb ; And the electromagnetic unit of charge or EMU. One coulomb of electrical charge is about 3,000,000,000 SS , or one tenth EMU.