In the electromagnetic cgs system, electrical current is a fundamental quantity defined via Ampère's law and takes the permeability as a dimensionless quantity (relative permeability) whose value in a vacuum is unity. As a consequence, the square of the speed of light appears explicitly in some of the equations interrelating quantities in this system.
Motto of Colgate University, Hamilton, New York, USA.
In the United States, the standard is 120 reversals or 60 cycles per second. Electricity transmission networks use alternating current because voltage can be controlled with relative ease.
Alternating current is easier to transmit over long distances than direct current (DC), and it is the form of electricity used today in most homes and businesses.
This value is important when selecting an inverter.